U.S. patent application number 13/473859 was filed with the patent office on 2012-11-22 for apparatus and method of protecting power receiver of wireless power transmission system.
This patent application is currently assigned to Samsung Electronics Co., Ltd.. Invention is credited to Jin Sung Choi, Young Tack Hong, Dong Zo Kim, Ki Young Kim, Nam Yun Kim, Sang Wook Kwon, Eun Seok Park, Yun Kwon Park, Young Ho Ryu, Chang Wook Yoon.
Application Number | 20120293009 13/473859 |
Document ID | / |
Family ID | 47174412 |
Filed Date | 2012-11-22 |
United States Patent
Application |
20120293009 |
Kind Code |
A1 |
Kim; Dong Zo ; et
al. |
November 22, 2012 |
APPARATUS AND METHOD OF PROTECTING POWER RECEIVER OF WIRELESS POWER
TRANSMISSION SYSTEM
Abstract
An apparatus and method of protecting a power receiver of a
wireless power transmission system are provided. A wireless power
receiver includes a rectifier comprising an input and an output,
and configured to receive a signal through the input, to rectify
the signal to produce a rectified signal, and to output the
rectified signal through the output, and a capacitor connected to
the output of the rectifier and to ground. The wireless power
receiver further includes a direct current-to-direct current
(DC/DC) converter connected to the output of the rectifier and to a
load, and configured to convert the rectified signal to a power,
and to provide the power to the load, and a device configured to
create a short circuit to protect the rectifier and/or the
capacitor when a voltage greater than a threshold voltage is
applied to the input of the rectifier and/or the output of the
rectifier.
Inventors: |
Kim; Dong Zo; (Yongin-si,
KR) ; Kwon; Sang Wook; (Seongnam-si, KR) ;
Kim; Ki Young; (Yongin-si, KR) ; Kim; Nam Yun;
(Seoul, KR) ; Park; Yun Kwon; (Dongducheon-si,
KR) ; Park; Eun Seok; (Yongin-si, KR) ; Ryu;
Young Ho; (Yongin-si, KR) ; Yoon; Chang Wook;
(Seoul, KR) ; Choi; Jin Sung; (Seoul, KR) ;
Hong; Young Tack; (Seongnam-si, KR) |
Assignee: |
Samsung Electronics Co.,
Ltd.
Suwon-si
KR
|
Family ID: |
47174412 |
Appl. No.: |
13/473859 |
Filed: |
May 17, 2012 |
Current U.S.
Class: |
307/104 ;
361/91.1; 361/91.5 |
Current CPC
Class: |
H02J 7/00047 20200101;
H02J 7/00036 20200101; B60L 53/126 20190201; H02H 7/1252 20130101;
H02J 7/025 20130101; H02J 50/80 20160201; Y02T 90/12 20130101; Y02T
10/70 20130101; Y02T 10/7072 20130101; H02J 50/12 20160201; Y02T
90/14 20130101 |
Class at
Publication: |
307/104 ;
361/91.1; 361/91.5 |
International
Class: |
H02J 17/00 20060101
H02J017/00; H02H 3/20 20060101 H02H003/20 |
Foreign Application Data
Date |
Code |
Application Number |
May 17, 2011 |
KR |
10-2011-0046278 |
May 24, 2011 |
KR |
10-2011-0049243 |
Apr 2, 2012 |
KR |
10-2012-0033957 |
Claims
1. A wireless power receiver comprising: a rectifier comprising an
input and an output, and configured to receive a signal through the
input, to rectify the signal to produce a rectified signal, and to
output the rectified signal through the output; a capacitor
connected to the output of the rectifier and to ground; a direct
current-to-direct current (DC/DC) converter connected to the output
of the rectifier and to a load, and configured to convert the
rectified signal to a power, and to provide the power to the load;
and a device configured to create a short circuit to protect the
rectifier and/or the capacitor when a voltage greater than a
threshold voltage is applied to the input of the rectifier and/or
the output of the rectifier.
2. The wireless power receiver of claim 1, wherein the device is
further configured to reduce a voltage applied to the rectifier
and/or the capacitor to protect the rectifier and/or the capacitor
when the voltage greater than the threshold voltage is applied to
the input of the rectifier and/or the output of the rectifier.
3. The wireless power receiver of claim 1, wherein: the signal is a
differential signal; the rectifier further comprises another
inputs, and is further configured to receive the differential
signal through the input and the other input, and to rectify the
differential signal to produce the rectified signal; and the device
is connected between the two inputs of the rectifier.
4. The wireless power receiver of claim 1, wherein a capacitance of
the device is less than or equal to 50 picofarads (pF).
5. The wireless power receiver of claim 1, wherein: the rectifier
comprises a Schottky diode; and a breakdown voltage of the device
is 3 volts (V) to 5V less than a peak reverse voltage of the
Schottky diode.
6. The wireless power receiver of claim 1, wherein the device is
connected to the capacitor and to the ground.
7. The wireless power receiver of claim 1, wherein the DC/DC
converter comprises a DC/DC buck converter.
8. A wireless power receiver comprising: a rectifier comprising an
input and an output, and configured to receive a signal through the
input, to rectify the signal to produce a rectified signal, and to
output the rectified signal through the output; a capacitor
connected to the output of the rectifier and to ground; a direct
current-to-direct current (DC/DC) converter connected to the output
of the rectifier and to a load, and configured to convert the
rectified signal to a power, and to provide the power to the load;
a switch unit connected to the input of the rectifier; and a
protection unit configured to control the switch unit to open or
close based on a voltage of the rectified signal.
9. The wireless power receiver of claim 8, wherein: the protection
unit is further configured to control the switch unit to close when
the voltage of the rectified signal is less than a threshold, to
enable the rectifier to receive the signal through the switch unit
and the input; and the protection unit is further configured to
control the switch unit to open when the voltage of the rectified
signal is greater than the threshold, to block the rectifier from
receiving the signal through the switch unit and the input.
10. The wireless power receiver of claim 8, wherein the switch unit
comprises a p-channel metal-oxide-semiconductor field-effect
transistor (PMOSFET) switch.
11. The wireless power receiver of claim 8, wherein the protection
unit comprises: a voltage adjustor configured to adjust a voltage
of the power to generate a first comparator input signal; a first
voltage divider configured to divide the voltage of the rectified
signal to generate a second comparator input signal; a comparator
configured to compare the first comparator input signal and the
second comparator input signal, and to output a comparator output
signal based on a result the comparison; and a second voltage
divider configured to divide a voltage of the comparator output
signal to generate a switch control signal to control the switch
unit to open or close.
12. The wireless power receiver of claim 11, wherein: the
comparator comprises a positive input connected to the first
voltage divider to receive the second comparator input signal, a
negative input connected to the voltage adjustor to receive the
first comparator input signal, and an output to output the
comparator output signal; the first voltage divider comprises a
first resistor connected to the positive input of the comparator
and to the output of the rectifier, and a second resistor connected
to the positive input of the comparator and to the ground; and the
second voltage divider comprises a third resistor connected to the
switch unit and to the output of the comparator, and a fourth
resistor connected to the output of the comparator and to the
ground.
13. The wireless power receiver of claim 11, wherein: the power
charges the load; the protection unit is further configured to
output the switch control signal to control the switch unit to
close while the load is being charged; and the protection unit is
further configured to output the switch control signal to control
the switch unit to open when the load is fully charged.
14. The wireless power receiver of claim 11, further comprising: a
communication/control unit configured to receive, from the
protection unit, the switch control signal, and transmit, to a
wireless power transmitter that transmits the signal to the
rectifier, a power transmission suspension signal based on the
switch control signal.
15. The wireless power receiver of claim 14, wherein: the power
charges the load; the protection unit is further configured to
generate the switch control signal to comprise a first value when
the load is being charged, and a second value when the load is
fully charged; and the communication/control unit is further
configured to transmit the power transmission suspension signal
when the switch control signal changes between the first value and
the second value, a N number of times, N being an integer greater
than or equal to 1.
16. A method of receiving a wireless power, comprising: rectifying
a signal received from a resonator; converting the rectified signal
to a power; providing the power to a load; and providing or
blocking the rectifying of the signal, based on a voltage of the
rectified signal.
17. The method of claim 16, wherein the providing or blocking of
the rectifying of the signal comprises: adjusting a voltage of the
power to generate a first comparator input signal; dividing a
voltage of the rectified signal to generate a second comparator
input signal; comparing the first comparator input signal and the
second comparator input signal to output a comparator output signal
based on a result the comparison; and dividing a voltage of the
comparator output signal to generate a switch control signal to
provide or block the rectifying of the signal.
18. The method of claim 17, further comprising: transmitting, to a
wireless power transmitter that transmits the signal to the
resonator, a power transmission suspension signal based on the
switch control signal.
19. The method of claim 18, wherein: the power charges the load;
the switch control signal comprises a first value when the load is
being charged, and a second value when the load is fully charged;
and the transmitting of the power transmission suspension signal
comprises: counting a number of times the switch control signal
changes between the first value and the second value; and
transmitting the power transmission suspension signal when the
number of times the switch control signal changes is greater than
or equal to N, N being an integer greater than or equal to 1.
20. A non-transitory computer-readable storage medium storing a
program comprising instructions to cause a computer to perform the
method of claim 16.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application claims the benefit under 35 U.S.C.
.sctn.119(a) of Korean Patent Application No. 10-2011-0046278,
filed on May 17, 2011, Korean Patent Application No.
10-2011-0049243, filed on May 24, 2011, and Korean Patent
Application No. 10-2012-0033957, filed on Apr. 2, 2012, in the
Korean Intellectual Property Office, the entire disclosures of
which are incorporated herein by reference for all purposes.
BACKGROUND
[0002] 1. Field
[0003] The following description relates to an apparatus and method
for wireless power transmission, and more particularly, to an
apparatus and method of protecting a power receiver in a wireless
power transmission system.
[0004] 2. Description of Related Art
[0005] A wireless power refers to energy transferred from a
wireless power transmission apparatus to a wireless power reception
apparatus, via magnetic coupling. A method of transmitting a
wireless power has been provided for a number of products, ranging
from an electric vehicle transmitting a power greater than or equal
to a few kilowatts (kW), to a high power application consuming a
power greater than or equal to 100 W and a low power application
consuming a power less than or equal to 10 W. The low power
application may be used for, e.g., a mobile device.
[0006] A wireless power reception apparatus may charge a battery
using a received energy. A wireless power transmission and charging
system includes a source device and a target device. The source
device wirelessly transmits a power. On the other hand, the target
device wirelessly receives a power. In other words, the source
device may be referred to as a wireless power transmission
apparatus, and the target device may be referred to as a wireless
power reception apparatus.
[0007] In an example, resonance-type wireless power transmission
may provide a high degree of freedom, in terms of positions of a
source device and a target device. The source device includes a
source resonator, and the target device includes a target
resonator. As an aspect, magnetic coupling or resonance coupling
may be formed between the source resonator and the target
resonator. The source device and the target device may communicate
with each other. During communications, the transmission or
reception of control and state information may occur. A portion of
the source device that transmits a wireless power may be referred
to as a power transmitter, and a portion of the target device that
receives a wireless power may be referred to as a power
receiver.
SUMMARY
[0008] In one general aspect, there is provided a wireless power
receiver including a rectifier including an input and an output,
and configured to receive a signal through the input, to rectify
the signal to produce a rectified signal, and to output the
rectified signal through the output. The wireless power receiver
further includes a capacitor connected to the output of the
rectifier and to ground. The wireless power receiver further
includes a direct current-to-direct current (DC/DC) converter
connected to the output of the rectifier and to a load, and
configured to convert the rectified signal to a power, and to
provide the power to the load. The wireless power receiver further
includes a device configured to create a short circuit to protect
the rectifier and/or the capacitor when a voltage greater than a
threshold voltage is applied to the input of the rectifier and/or
the output of the rectifier.
[0009] The device is further configured to reduce a voltage applied
to the rectifier and/or the capacitor to protect the rectifier
and/or the capacitor when the voltage greater than the threshold
voltage is applied to the input of the rectifier and/or the output
of the rectifier.
[0010] The signal is a differential signal. The rectifier further
includes another inputs, and is further configured to receive the
differential signal through the input and the other input, and to
rectify the differential signal to produce the rectified signal.
The device is connected between the two inputs of the
rectifier.
[0011] A capacitance of the device is less than or equal to 50
picofarads (pF).
[0012] The rectifier includes a Schottky diode. A breakdown voltage
of the device is 3 volts (V) to 5V less than a peak reverse voltage
of the Schottky diode.
[0013] The device is connected to the capacitor and to the
ground.
[0014] The DC/DC converter includes a DC/DC buck converter.
[0015] In another general aspect, there is provided a wireless
power receiver including a rectifier including an input and an
output, and configured to receive a signal through the input, to
rectify the signal to produce a rectified signal, and to output the
rectified signal through the output. The wireless power receiver
further includes a capacitor connected to the output of the
rectifier and to ground. The wireless power receiver further
includes a direct current-to-direct current (DC/DC) converter
connected to the output of the rectifier and to a load, and
configured to convert the rectified signal to a power, and to
provide the power to the load. The wireless power receiver further
includes a switch unit connected to the input of the rectifier. The
wireless power receiver further includes a protection unit
configured to control the switch unit to open or close based on a
voltage of the rectified signal.
[0016] The protection unit is further configured to control the
switch unit to close when the voltage of the rectified signal is
less than a threshold, to enable the rectifier to receive the
signal through the switch unit and the input. The protection unit
is further configured to control the switch unit to open when the
voltage of the rectified signal is greater than the threshold, to
block the rectifier from receiving the signal through the switch
unit and the input.
[0017] The switch unit includes a p-channel
metal-oxide-semiconductor field-effect transistor (PMOSFET)
switch.
[0018] The protection unit includes a voltage adjustor configured
to adjust a voltage of the power to generate a first comparator
input signal. The protection unit further includes a first voltage
divider configured to divide the voltage of the rectified signal to
generate a second comparator input signal. The protection unit
further includes a comparator configured to compare the first
comparator input signal and the second comparator input signal, and
to output a comparator output signal based on a result the
comparison. The protection unit further includes a second voltage
divider configured to divide a voltage of the comparator output
signal to generate a switch control signal to control the switch
unit to open or close.
[0019] The comparator includes a positive input connected to the
first voltage divider to receive the second comparator input
signal, a negative input connected to the voltage adjustor to
receive the first comparator input signal, and an output to output
the comparator output signal. The first voltage divider includes a
first resistor connected to the positive input of the comparator
and to the output of the rectifier, and a second resistor connected
to the positive input of the comparator and to the ground. The
second voltage divider includes a third resistor connected to the
switch unit and to the output of the comparator, and a fourth
resistor connected to the output of the comparator and to the
ground.
[0020] The power charges the load. The protection unit is further
configured to output the switch control signal to control the
switch unit to close while the load is being charged. The
protection unit is further configured to output the switch control
signal to control the switch unit to open when the load is fully
charged.
[0021] The wireless power receiver further includes a
communication/control unit configured to receive, from the
protection unit, the switch control signal, and transmit, to a
wireless power transmitter that transmits the signal to the
rectifier, a power transmission suspension signal based on the
switch control signal.
[0022] The power charges the load. The protection unit is further
configured to generate the switch control signal to include a first
value when the load is being charged, and a second value when the
load is fully charged. The communication/control unit is further
configured to transmit the power transmission suspension signal
when the switch control signal changes between the first value and
the second value, a N number of times, N being an integer greater
than or equal to 1.
[0023] In another general aspect, there is provided a method of
receiving a wireless power, including rectifying a signal received
from a resonator. The method further includes converting the
rectified signal to a power, and providing the power to a load. The
method further includes providing or blocking the rectifying of the
signal, based on a voltage of the rectified signal.
[0024] The providing or blocking of the rectifying of the signal
includes adjusting a voltage of the power to generate a first
comparator input signal, dividing a voltage of the rectified signal
to generate a second comparator input signal, comparing the first
comparator input signal and the second comparator input signal to
output a comparator output signal based on a result the comparison,
and dividing a voltage of the comparator output signal to generate
a switch control signal to provide or block the rectifying of the
signal.
[0025] The method further includes transmitting, to a wireless
power transmitter that transmits the signal to the resonator, a
power transmission suspension signal based on the switch control
signal.
[0026] The power charges the load. The switch control signal
includes a first value when the load is being charged, and a second
value when the load is fully charged. The transmitting of the power
transmission suspension signal includes counting a number of times
the switch control signal changes between the first value and the
second value, and transmitting the power transmission suspension
signal when the number of times the switch control signal changes
is greater than or equal to N, N being an integer greater than or
equal to 1.
[0027] A non-transitory computer-readable storage medium stores a
program including instructions to cause a computer to perform the
method.
[0028] Other features and aspects may be apparent from the
following detailed description, the drawings, and the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1 is a diagram illustrating an example of a wireless
power transmission system.
[0030] FIG. 2 is a diagram illustrating an example of a wireless
power transmitter.
[0031] FIG. 3 is a diagram illustrating another example of a
wireless power transmitter.
[0032] FIGS. 4 through 8 are diagrams illustrating examples of
resonators.
[0033] FIG. 9 is a diagram illustrating an example of an equivalent
circuit of a resonator of FIG. 3.
[0034] FIG. 10 is a diagram illustrating an example of a
rectification system of a wireless power receiver.
[0035] FIG. 11 is a diagram illustrating an example of a
battery.
[0036] FIG. 12 is a graph illustrating an example of a charging of
a battery according to a charging time.
[0037] FIG. 13 is a diagram illustrating an example of results of a
simulation of magnitudes of voltages applied, respectively, to a
front end and a back end of a rectifier when a load impedance
corresponds to 10 ohms (.OMEGA.).
[0038] FIG. 14 is a diagram illustrating an example of results of a
simulation of magnitudes of voltages applied, respectively, to a
front end and a back end of a rectifier when a load impedance
corresponds to 100 .OMEGA..
[0039] FIG. 15 is a diagram illustrating an example of results of a
simulation of magnitudes of voltages applied, respectively, to a
front end and a back end of a rectifier when a load impedance
corresponds to 1 kilo-ohm (k.OMEGA.).
[0040] FIG. 16 is a diagram illustrating an example of a wireless
power receiver including a short-type protection circuit.
[0041] FIG. 17 is a diagram illustrating another example of a
wireless power receiver including a short-type protection
circuit.
[0042] FIG. 18 is a diagram illustrating an example of a wireless
power receiver including an open-type protection circuit.
[0043] FIG. 19 is a diagram illustrating an example of an operation
of a wireless power receiver including an open-type protection
circuit in a normal charging mode.
[0044] FIG. 20 is a diagram illustrating an example of an operation
of a wireless power receiver including an open-type protection
circuit in a full charging mode.
[0045] FIG. 21 is a diagram illustrating an example of operations
of a wireless power transmitter and a wireless power receiver in a
full charging mode.
[0046] FIG. 22 is a flowchart illustrating an example of a method
of receiving a wireless power.
[0047] FIG. 23 is a diagram illustrating an example of an electric
vehicle charging system.
[0048] FIGS. 21A through 22B are diagrams illustrating examples of
applications in which a wireless power receiver and a wireless
power transmitter may be mounted.
[0049] FIG. 23 is a diagram illustrating an example of a wireless
power transmitter and a wireless power receiver.
[0050] Throughout the drawings and the detailed description, unless
otherwise described, the same drawing reference numerals will be
understood to refer to the same elements, features, and structures.
The relative size and depiction of these elements may be
exaggerated for clarity, illustration, and convenience.
DETAILED DESCRIPTION
[0051] The following detailed description is provided to assist the
reader in gaining a comprehensive understanding of the methods,
apparatuses, and/or systems described herein. Accordingly, various
changes, modifications, and equivalents of the methods,
apparatuses, and/or systems described herein will be suggested to
those of ordinary skill in the art. The progression of processing
steps and/or operations described is an example; however, the
sequence of and/or operations is not limited to that set forth
herein and may be changed as is known in the art, with the
exception of steps and/or operations necessarily occurring in a
certain order. Also, description of well-known functions and
constructions may be omitted for increased clarity and
conciseness.
[0052] A method of protecting a power receiver, including a load,
in resonance-type wireless power transmission will be described
hereinafter. The load may correspond to a battery. Herein, the
terms "load", "battery", and "load battery" may be used to denote
the same meaning, and may be interchangeable with one another. The
load may include a charger circuit for a safe charging operation.
The charger circuit may adjust conditions of a voltage and a
current, depending on an initial charging period, a period during
which charging is being performed, a period during which full
charging is completed, and/or the like. Also, when the load is
fully charged, a protection circuit module (PCM) blockage mode may
be operated, and a path to the load may be blocked. The blockage
may result in a change in an impedance of the load, whereby a high
voltage may be applied to a rectifier and a power higher than a
power requested by the load may be received. In the following
examples, a method of resolving a problem of damages to the
rectifier and a rectifier capacitor, which may occur due to a high
voltage or a high power, will be provided.
[0053] In the following examples, a short-type protection circuit
and an open-type protection circuit that may protect a
rectification system, will be provided. Also, in the following
examples, a full charging sensing method by which a communication
signal indicating that a power transmission is to be suspended may
be transmitted to a power transmitter when a full charge is sensed,
will be provided. In the full charge sensing method, a wireless
power reception apparatus may complete a wireless charging process
stably.
[0054] FIG. 1 illustrates an example of a wireless power
transmission system. The wireless power transmission system
includes a source device 110 and a target device 120.
[0055] The source device 110 includes an alternating
current-to-direct current (AC/DC) converter 111, a power detector
113, a power converter 114, a control/communication unit 115, and a
source resonator 116. The target device 120 includes a target
resonator 121, a rectification unit 122, a DC-to-DC (DC/DC)
converter 123, a switch unit 124, a charging unit 125, and a
control/communication unit 126.
[0056] The AC/DC converter 111 rectifies an AC voltage in a band of
tens of hertz (Hz) output from a power supply 112 to generate a DC
voltage. The AC/DC converter 111 may output a DC voltage of a
predetermined level, or may adjust an output level of a DC voltage
based on the control of the control/communication unit 115.
[0057] The power detector 113 detects an output current and an
output voltage of the AC/DC converter 111, and transfers, to the
control/communication unit 115, information on the detected current
and the detected voltage. In addition, the power detector 113
detects an input current and an input voltage of the power
converter 114.
[0058] The power converter 114 uses a switching pulse signal in a
band of a few megahertz (MHz) to tens of MHz to convert a DC
voltage of a predetermined level to an AC voltage, to generate a
power. As an example, the power converter 114 uses a resonance
frequency to convert a DC voltage to an AC voltage, and generates a
communication power used for communication and/or a charging power
used to charge. The communication power and the charging power are
used in the target device 120. The communication power may refer to
an energy used to activate a communication module and a processor
of the target device 120. Accordingly, the communication power may
be referred to as a "wake-up power". Additionally, the
communication power may be transmitted in the form of a constant
wave (CW) for a predetermined period of time. The charging power
may refer to an energy used to charge a battery connected to the
target device 120 or included in the target device 120. The
charging power may continue to be transmitted, at a higher power
level than the communication power, for a predetermined period of
time. For example, the communication power may have a power level
of 0.1 Watt (W) to 1 W, and the charging power may have a power
level of 1 W to 20 W.
[0059] The control/communication unit 115 may control a frequency
of a switching pulse signal. The frequency of the switching pulse
signal may be determined under the control of the
control/communication unit 115. The control/communication unit 115
may control the power converter 114 to generate a modulation signal
to be transmitted to the target device 120. In other words, the
control/communication unit 115 may use in-band communication to
transmit various messages to the target device 120. Additionally,
the control/communication unit 115 may detect a reflected wave, and
the control/communication unit 115 may demodulate a signal received
from the target device 120 through an envelope of the detected
reflected wave.
[0060] The control/communication unit 115 may use various schemes
to generate a modulation signal for in-band communication. The
control/communication unit 115 may turn on or off the switching
pulse signal, or may perform delta-sigma modulation, to generate
the modulation signal. Additionally, the control/communication unit
115 may generate a pulse-width modulation (PWM) signal with a
predetermined envelope.
[0061] The control/communication unit 115 may perform out-band
communication that employs a separate communication channel,
instead of a resonance frequency. The control/communication unit
115 may include a communication module. The communication module
may include, for example, a ZigBee module, a Bluetooth module,
and/or the like. The control/communication unit 115 may transmit
data to the target device 120 using the out-band communication, or
receive data from the target device 120 using the out-band
communication.
[0062] The source resonator 116 transfers an electromagnetic energy
to the target resonator 121. As an example, the source resonator
116 transfers, to the target device 120, a communication power used
for communication and/or a charging power used to charge, using a
magnetic coupling with the target resonator 121.
[0063] The target resonator 121 receives the electromagnetic energy
from the source resonator 116. As an example, the target resonator
121 receives, from the source device 110, the communication power
and/or charging power, using the magnetic coupling with the source
resonator 116. As another example, the target resonator 121 may use
the in-band communication to receive various messages from the
source device 110.
[0064] The rectification unit 122 rectifies an AC voltage to
generate a DC voltage. In this example, the AC voltage is received
from the target resonator 121.
[0065] The DC/DC converter 123 adjusts a level of the DC voltage
output from the rectification unit 122 based on a capacity of the
charging unit 125. For example, the DC/DC converter 123 may adjust
to, for example, 3 volt (V) through 10 V, the level of the DC
voltage output from the rectification unit 122.
[0066] The switch unit 124 is turned on or off under the control of
the control/communication unit 126. In response to the switch unit
124 being turned off, the control/communication unit 115 detects a
reflected wave. In other words, in response to the switch unit 124
being turned off, the magnetic coupling between the source
resonator 116 and the target resonator 121 is substantially
reduced.
[0067] The charging unit 125 may include a battery. The charging
unit 125 may use a DC voltage output from the DC/DC converter 123
to charge the battery.
[0068] The control/communication unit 126 may use a resonance
frequency to perform in-band communication to transmit and/or
receive data. During the in-band communication, the
control/communication unit 126 may detect a signal between the
target resonator 121 and the rectification unit 122, or detect an
output signal of the rectification unit 122 to demodulate a
received signal. In other words, the control/communication unit 126
may demodulate a message received using the in-band
communication.
[0069] As another example, the control/communication unit 126 may
adjust an impedance of the target resonator 121 to modulate a
signal to be transmitted to the source device 110. As an example,
the control/communication unit 126 may turn on or off the switch
unit 124 to modulate the signal to be transmitted to the source
device 110. For example, the control/communication unit 126 may
increase the impedance of the target resonator 121. Based on the
increase of the impedance of the target resonator 121, a reflected
wave may be detected in the control/communication unit 115. In this
example, depending on whether the reflected wave is detected, the
control/communication unit 115 may detect a binary number "0" or
"1".
[0070] The control/communication unit 126 may also perform out-band
communication that employs a communication channel. The
control/communication unit 126 may include a communication module.
The communication module may include, for example, a ZigBee module,
a Bluetooth module, and/or the like. The control/communication unit
126 may transmit, to the source device 110, using the out-band
communication, or receive data, from the source device 110, using
the out-band communication.
[0071] FIG. 2 illustrates an example of a wireless power
transmitter. The wireless power transmitter includes a source
resonator 210, a sub-resonator 220, and a magnetic field
distribution controller 230.
[0072] The source resonator 210 forms a magnetic coupling with a
target resonator. The source resonator 210 wirelessly transmits
power to a target device through the magnetic coupling. The source
resonator 210 may have a loop shape as illustrated in FIG. 2. In
examples, the loop shape may be implemented in various shapes. For
example, the shapes may include a spiral shape, a helical shape,
and/or the like.
[0073] Additionally, the wireless power transmitter may include a
matcher (not illustrated) to be used in impedance matching. The
matcher may adjust a strength of a magnetic field of the source
resonator 210 to an appropriate level. An impedance of the source
resonator 210 may be determined by the matcher. The matcher may
have the same shape as the source resonator 210. Additionally, the
matcher may have a predetermined location relationship with a
capacitor located in the source resonator 210 to adjust the
strength of the magnetic field. For example, the matcher may be
electrically connected to the source resonator 210 in both ends of
the capacitor.
[0074] As an example, the matcher may be located within a loop of
the loop structure of the source resonator 210. The matcher may
change the physical shape of the matcher to adjust the impedance of
the source resonator 210.
[0075] The sub-resonator 220 is located within the source resonator
210. A plurality of sub-resonators may be located within the source
resonator 210. Additionally, a sub-sub-resonator may be located
within the sub-resonator 220. The sub-resonator 220 influences a
distribution of a magnetic field formed within the source resonator
210. For example, a current flowing in the source resonator 210
forms a magnetic field, and the formed magnetic field induces a
current to the sub-resonator 220. In this example, a distribution
of the magnetic field formed within the source resonator 210 is
determined based on a direction of the current flowing in the
source resonator 210 and in the sub-resonator 220. As another
example, the direction of the current flowing in the sub-resonator
220 is determined based on a ratio of a resonance frequency of the
sub-resonator 220 to a resonance frequency of the source resonator
210.
[0076] The resonance frequency of the source resonator 210 is
related to an inductance value L and a capacitance value C of the
source resonator 210. Similarly, the resonance frequency of the
sub-resonator 220 is related to an inductance value and a
capacitance value of the sub-resonator 220.
[0077] The magnetic field distribution controller 230 is located in
a predetermined area within the source resonator 210. The magnetic
field distribution controller 230 controls the direction of the
current flowing in the source resonator 210 or in the sub-resonator
220. The magnetic field distribution controller 230 controls the
distribution of the magnetic field formed within the source
resonator 210. The direction of the current flowing in the source
resonator 210, or the direction of the current flowing in the
sub-resonator 220, are related to the ratio of the resonance
frequency of the sub-resonator 220 to the resonance frequency of
the source resonator 210.
[0078] The magnetic field distribution controller 230 controls the
resonance frequency of the source resonator 210, or the resonance
frequency of the sub-resonator 220. As an example, the magnetic
field distribution controller 230 controls the resonance frequency
of the source resonator 210 based on changing the capacitance of
the source resonator 210. As another example, the magnetic field
distribution controller 230 controls the resonance frequency of the
sub-resonator 220 based on adjusting the capacitance and the
inductance of the sub-resonator 220. The magnetic field
distribution controller 230 adjusts a length and a width of a line
that forms the sub-resonator 220 to control the inductance value of
the sub-resonator 220.
[0079] The magnetic field distribution controller 230 controls the
direction of the current flowing in the source resonator 210, or
the direction of the current flowing in the sub-resonator 220, so
that the strength of the magnetic field formed within the source
resonator 210 may be increased or decreased.
[0080] As another example, the magnetic field distribution
controller 230 controls the distribution of the magnetic field, so
that the magnetic field is uniformly distributed in the source
resonator 210. As another example, the magnetic field distribution
controller 230 controls the resonance frequency of the
sub-resonator 220, and the magnetic field to be uniformly
distributed in the source resonator 210. The configuration of the
sub-resonator 220 will be further described with reference to FIG.
8.
[0081] The magnetic field distribution controller 230 may use a
sub-sub-resonator to control the distribution of the magnetic field
formed within the source resonator 210. The magnetic field
distribution controller 230 may control a resonance frequency of
the sub-sub-resonator, and may compensate for the uniform
distribution of the magnetic field formed within the source
resonator 210. The magnetic field distribution controller 230 may
control the direction of the current flowing in the sub-resonator
220, a direction of a current flowing in the sub-sub-resonator, and
the distribution of the magnetic field. The sub-sub-resonator may
be located in the sub-resonator 220. The sub-sub-resonator may
support the sub-resonator 220, and may compensate for the
distribution of the magnetic field formed within the source
resonator 210, so that the magnetic field may be uniformly
distributed. The sub-sub-resonator may compensate for the
distribution of the magnetic field adjusted by the sub-resonator
220, so that the magnetic field may be uniformly distributed in the
source resonator 210.
[0082] The magnetic field distribution controller 230 may include
at least one coil. The coil may be used to induce the magnetic
field formed within the source resonator 210 towards the center of
the source resonator 210. As another example, the magnetic field
distribution controller 230 may use the coil to control the
magnetic field formed within the source resonator 210 to be
uniformly distributed. The magnetic field distribution controller
230 may control a resonance frequency of the coil, so that a
current may flow in the coil in the same direction as the current
flowing in the source resonator 210.
[0083] In an example, at least one coil may be located in the
center of the source resonator 210, and the coil may form at least
one loop structure with different sizes. The magnetic field
distribution controller 230 may use the coil of various sizes to
more precisely control the magnetic field formed within the source
resonator 210.
[0084] In another example, at least one coil having the same shape
as another coil may be located in a predetermined position within
the source resonator 210. The coil having the same shape as another
coil may be located in various areas within the source resonator
210. Under the control of the magnetic field distribution
controller 230, the coil having the same shape as another coil may
increase or decrease the strength of the magnetic field formed
within the source resonator 210 in the various areas in which the
coil having the same shape as another coil is located.
[0085] In yet another example, the coil may be located in the
center of the source resonator 210. The coil may be formed in a
spiral shape. As another example, the coil may be formed with
various shapes, and coil may adjust the magnetic field formed
within the source resonator 210.
[0086] The magnetic field distribution controller 230 may include a
plurality of shielding layers. The shielding layers may have
different sizes and heights located at the center of the source
resonator 210, and may have a loop structure. Due to the shielding
layers being located at the center of the source resonator 210 and
having the loop structure, the magnetic field distribution
controller 230 may induce the magnetic field formed within the
source resonator 210 to be uniformly distributed. A magnetic flux
of the magnetic field formed within the source resonator 210 may be
refracted from the shielding layers, and the magnetic flux of the
magnetic field may be more concentrated on the center of the source
resonator 210.
[0087] The magnetic field distribution controller 230 may include,
for example, a layer formed of a mu negative (MNG) material, a
double negative (DNG) material, or a magneto-dielectric material.
The magnetic field distribution controller 230 may refract the
magnetic flux of the magnetic field formed within the source
resonator 210, based on the layer, and may induce the magnetic
field to be uniformly distributed in the source resonator 210.
[0088] The magnetic field distribution controller 230 may adjust
widths of the shielding layers laminated in predetermined positions
of the source resonator 210 and the sub-resonator 220, and may
induce the magnetic field to be uniformly distributed within the
source resonator 210. Based on the widths of the shielding layers,
a refractive level of the magnetic flux of the magnetic field
formed within the source resonator 210, may be changed.
Accordingly, the magnetic field distribution controller 230 may
adjust the widths of the shielding layers to control the magnetic
field to be uniformly distributed within the source resonator
210.
[0089] A target device may be located on the source resonator 210
of a pad type. In this example, a gap between the source resonator
210 and the target device may be less than a 2 or 3 centimeters
(cm). Accordingly, a parasitic capacitor may be formed between the
source resonator 210 and the target device. The parasitic capacitor
may influence the resonance frequency of the source resonator 210.
The magnetic field distribution controller 230 may adjust widths
and thicknesses of the shielding layers laminated in predetermined
positions of the source resonator 210 and the sub-resonator 220,
and may offset a change in the resonance frequency of the source
resonator 210 due to the parasitic capacitor.
[0090] FIG. 3 illustrates an example of a wireless power
transmitter 300, e.g., a source resonator. The source resonator may
form a magnetic coupling with a target resonator. The source
resonator may wirelessly transmit a power to the target device via
the magnetic coupling. The source resonator includes a first
transmission line, a first conductor 321, a second conductor 322,
and at least one first capacitor 330.
[0091] The first capacitor 330 is inserted in series between a
first signal conducting portion 311 and a second signal conducting
portion 312 in the first transmission line. An electric field is
confined to be within the first capacitor 330. For example, the
first transmission line may include at least one conductor in an
upper portion of the first transmission line, may also include at
least one conductor in a lower portion of the first transmission
line. Current may flow through the at least one conductor disposed
in the upper portion of the first transmission line. The at least
one conductor disposed in the lower portion of the first
transmission line may be electrically grounded. For example, a
conductor disposed in an upper portion of the first transmission
line may be separated into the first signal conducting portion 311
and the second signal conducting portion 312. A conductor disposed
in a lower portion of the first transmission line may be referred
to as a first ground conducting portion 313.
[0092] The source resonator of FIG. 3 has a two-dimensional (2D)
structure. The first transmission line includes the first signal
conducting portion 311 and the second signal conducting portion
312. The first signal conducting portion 311 and the second signal
conducting portion 312 are located in the upper portion of the
first transmission line. In addition, the first transmission line
includes the first ground conducting portion 313 in the lower
portion of the first transmission line. The first signal conducting
portion 311 and the second signal conducting portion 312 face the
first ground conducting portion 313. The current flows through the
first signal conducting portion 311 and the second signal
conducting portion 312.
[0093] As one example, one end of the first signal conducting
portion 311 is connected to the first conductor 321. One end of the
second signal conducting portion 312 is connected to the second
conductor 322. The other ends of the first signal conducting
portion 311 and the second signal conducting portion 312 are both
connected to the first capacitor 330. Accordingly, the first signal
conducting portion 311, the second signal conducting portion 312,
the first ground conducting portion 313, and the conductors 321 and
322 are connected to each other. Thus, the source resonator has an
electrically closed-loop structure. The term "loop structure" may
have, for example, a polygonal structure, such as a circular
structure, a rectangular structure, and/or the like. "Having a loop
structure" may indicate that the circuit is electrically
closed.
[0094] The first capacitor 330 is inserted into an intermediate
portion of the first transmission line. For example, the first
capacitor 330 is inserted into a space between the first signal
conducting portion 311 and the second signal conducting portion
312. The first capacitor 330 may have a shape corresponding to a
lumped element, a distributed element, and/or the like. For
example, a distributed capacitor having the shape of the
distributed element may include zigzagged conductor lines and a
dielectric material having a high permittivity between the
zigzagged conductor lines.
[0095] In response to the first capacitor 330 being inserted into
the first transmission line instead of the space between the first
signal conducting portion 311 and the second signal conducting
portion 312, the source resonator may have a characteristic of a
metamaterial. The metamaterial may indicate a material having a
predetermined electrical property that has not been discovered in
nature, and thus, the meta material may have an artificially
designed structure. An electromagnetic characteristic of the
materials existing in nature may have a unique magnetic
permeability or a unique permittivity. Most materials may have a
positive magnetic permeability or a positive permittivity.
[0096] In the case of most materials, a right hand rule may be
applied to an electric field, a magnetic field, and a Poynting
vector, and thus, the corresponding materials having the right hand
rule applied may be referred to as right handed materials (RHMs).
As another example, the metamaterial having a magnetic permeability
or a permittivity absent in nature may be classified into an
epsilon negative (ENG) material, an MNG material, a DNG material, a
negative refractive index (NRI) material, a left-handed (LH)
material, and/or the like. The classification may be based on a
sign of the corresponding permittivity or magnetic
permeability.
[0097] In response to a capacitance of the first capacitor 330
inserted as the lumped element being appropriately determined, the
source resonator may have the characteristic of the metamaterial.
The source resonator may have a negative magnetic permeability
based on an adjustment of the capacitance of the first capacitor
330. Thus, the source resonator may also be referred to as an MNG
resonator. Various criteria may be used to determine the
capacitance of the first capacitor 330. For example, the various
criteria may include a criterion configured to enable the source
resonator to have the characteristic of the metamaterial, a
criterion configured to enable the source resonator to have a
negative magnetic permeability in a target frequency, a criterion
configured to enable the source resonator to have a zeroth order
resonance characteristic in the target frequency, and/or the like.
Based on any combination of the aforementioned criteria, the
capacitance of the first capacitor 330 may be determined.
[0098] The source resonator, also referred to as the MNG resonator,
may have a zeroth order resonance characteristic. The zeroth order
resonance characteristic may have, as a resonance frequency, a
frequency where a propagation constant is "0". Because the source
resonator may have the zeroth order resonance characteristic, the
resonance frequency may be independent of a physical size of the
MNG resonator. The MNG resonator may change the resonance frequency
based on an appropriate design of the first capacitor 330.
Accordingly, the physical size of the MNG resonator may not be
changed.
[0099] In a near field, an electric field may be concentrated on
the first capacitor 330 inserted into the first transmission line.
Accordingly, due to the first capacitor 330, the magnetic field may
become dominant in the near field. The MNG resonator may have a
relatively high Q-factor using the first capacitor 330 of the
lumped element, and thus, an enhancement of an efficiency of power
transmission may be possible. For example, the Q-factor may
indicate a level of an ohmic loss, or a ratio of a reactance with
respect to a resistance in the wireless power transmission. The
efficiency of the wireless power transmission may increase
corresponding to an increase in the Q-factor.
[0100] Although not illustrated in FIG. 3, a magnetic core may be
provided to pass through the MNG resonator. The magnetic core may
increase a power transmission distance.
[0101] Referring to FIG. 3, a sub-resonator includes a second
transmission line, a third conductor 351, a fourth conductor 352,
and at least one second capacitor 360. The second capacitor 360 is
inserted between a third signal conducting portion 341 and a fourth
signal conducting portion 342 in the second transmission line, and
an electric field is confined to be within the second capacitor
360. As an example, the second capacitor 360 is located in series
between the third signal conducting portion 341 and the fourth
signal conducting portion 342.
[0102] As illustrated in FIG. 3, the sub-resonator has a 2D
structure. The second transmission line includes the third signal
conducting portion 341 and the fourth signal conducting portion 342
in an upper portion of the second transmission line. In addition,
the second transmission line includes a second ground conducting
portion 343 in a lower portion of the second transmission line. The
third signal conducting portion 341 and the fourth signal
conducting portion 342 faces the second ground conducting portion
343. Current flows through the third signal conducting portion 341
and the fourth signal conducting portion 342.
[0103] As another example, one end of the third signal conducting
portion 341 is connected to the third conductor 351, and the other
end of the third signal conducting portion 341 is connected to the
second capacitor 360. One end of the fourth signal conducting
portion 342 is connected to the fourth conductor 352, and the other
end of the fourth signal conducting portion 342 is connected to the
second capacitor 360. Accordingly, the third signal conducting
portion 341, the fourth signal conducting portion 342, the second
ground conducting portion 343, the third conductor 351, and the
fourth conductor 352 is connected to each other. Thus, the
sub-resonator has an electrically closed-loop structure. The term
"loop structure" may refer to, for example, a polygonal structure,
such as a circular structure, a rectangular structure, and/or the
like. The second transmission line, the third conductor 351, and
the fourth conductor 352 may form, for example, a rectangular loop
structure, a circular loop structure, or a crossed loop
structure.
[0104] A magnetic field distribution controller may adjust a
resonance frequency of at least one sub-resonator based on a value
of the second capacitor 360, and a length and width of the second
transmission line. Thus, the resonance frequency of the
sub-resonator may differ from a resonance frequency of the source
resonator by a predetermined value.
[0105] The magnetic field distribution controller may adjust the
value of the second capacitor 360. For example, in response to the
value of the second capacitor 360 being changed, the resonance
frequency of the sub-resonator may also be changed. Accordingly,
the magnetic field distribution controller may adjust the value of
the second capacitor 360 to adjust the resonance frequency of the
sub-resonator to be greater than or less than the resonance
frequency of the source resonator. The magnetic field distribution
controller may adjust the resonance frequency of the sub-resonator
to be greater than or less than the resonance frequency of the
source resonator, so that a magnetic field formed in the center of
the source resonator may have substantially the same strength as a
magnetic field formed outside the source resonator.
[0106] FIGS. 4 through 8 illustrate examples of resonators. A
source resonator included in a wireless power transmitter may have
a structure as illustrated in FIGS. 4 through 8.
[0107] FIG. 4 illustrates an example of a resonator 400 having a
three-dimensional (3D) structure. The resonator 400 includes a
transmission line and a capacitor 420. The transmission line
includes a first signal conducting portion 411, a second signal
conducting portion 412, and a ground conducting portion 413. The
capacitor 420 is located in series between the first signal
conducting portion 411 and the second signal conducting portion 412
of the transmission line. An electric field is confined within the
capacitor 420.
[0108] As illustrated in FIG. 4, the resonator 400 has the 3D
structure. The transmission line includes the first signal
conducting portion 411 and the second signal conducting portion 412
in an upper portion of the resonator 400, and the resonator 400
includes the ground conducting portion 413 in a lower portion of
the resonator 400. The first signal conducting portion 411 and the
second signal conducting portion 412 face the ground conducting
portion 413. For example, current flows in an x-direction through
the first signal conducting portion 411 and the second signal
conducting portion 412. Due to the current, a magnetic field H(W)
is formed in a -y-direction. As another example, unlike the diagram
of FIG. 4, the magnetic field H(W) may be formed in a +y
direction.
[0109] One end of the first signal conducting portion 411 is
connected to a conductor 442, and the other end of the first signal
conducting portion 411 is connected to the capacitor 420. One end
of the second signal conducting portion 412 is grounded to a
conductor 441, and the other end of the second signal conducting
portion 412 is connected to the capacitor 420. Accordingly, the
first signal conducting portion 411, the second signal conducting
portion 412, the ground conducting portion 413, and the conductors
441 and 442 are connected to each other. Thus, the resonator 400
has an electrically closed-loop structure. The term "loop
structure" may refer to a polygonal structure, such as, for
example, a circular structure, a rectangular structure, and/or the
like. "Having a loop structure" may indicate being electrically
closed.
[0110] The capacitor 420 is inserted between the first signal
conducting portion 411 and the second signal conducting portion
412. The capacitor 420 may have a shape of a lumped element, a
distributed element, and/or the like. As an example, a distributed
capacitor having the shape of the distributed element may include
zigzagged conductor lines, and the distributed capacitor may have a
dielectric material having a relatively high permittivity located
between the zigzagged conductor lines.
[0111] The resonator 400, having the capacitor 420 inserted into
the transmission line, may have a metamaterial property. In
response to a capacitance of the capacitor inserted as the lumped
element being appropriately determined, the resonator 400 may have
the characteristic of the metamaterial. Because the resonator 400
may appropriately adjust the capacitance of the capacitor 420 to
have a negative magnetic permeability, the resonator 400 may also
be referred to as an MNG resonator. Various criteria may be applied
to determine the capacitance of the capacitor 420. For example, a
criterion configured to enable the resonator 400 to have the
characteristic of the metamaterial, a criterion configured to
enable the resonator 400 to have a negative magnetic permeability
in a target frequency, a criterion configured to enable the
resonator 400 to have a zeroth order resonance characteristic in
the target frequency, and/or the like, may be applied. The
capacitance of the capacitor 420 may be determined based on at
least one criterion among the aforementioned criteria.
[0112] The resonator 400, also referred to as the MNG resonator
400, may have a zeroth order resonance characteristic having, as a
resonance frequency, a frequency where a propagation constant is
"0". Because the resonator 400 may have the zeroth order resonance
characteristic, the resonance frequency may be independent of a
physical size of the MNG resonator 400. The MNG resonator 400 may
appropriately design the capacitor 420 to change the resonance
frequency. Accordingly, the physical size of the MNG resonator 400
may not be changed.
[0113] Referring to the MNG resonator 400 of FIG. 4, in a near
field, the electric field may be concentrated on the capacitor 420
inserted into the transmission line. Accordingly, the magnetic
field may become dominant in the near field due to the capacitor
420. For example, because the MNG resonator 400 having the
zeroth-order resonance characteristic may have characteristics
similar to a magnetic dipole, the magnetic field may become
dominant in the near field. A relatively small amount of the
electric field formed due to the insertion of the capacitor 420 may
be concentrated on the capacitor 420, and thus, the magnetic field
may become further dominant. The MNG resonator 400 may have a
relatively high Q-factor using the capacitor 420 of the lumped
element. Thus, enhancement of an efficiency of power transmission
is possible.
[0114] Also, the MNG resonator 400 includes a matcher 430
configured to perform impedance matching. The matcher 430
appropriately adjusts the strength of magnetic field of the MNG
resonator 400. The matcher 430 determines an impedance of the MNG
resonator 400. Current flows into and/or out of the MNG resonator
400 via a connector 440 connected to the ground conducting portion
413 or the matcher 430.
[0115] For example, as shown in FIG. 4, the matcher 430 is
positioned within the loop of the loop structure of the resonator
400. The matcher 430 changes the physical shape of the matcher 430
to adjust the impedance of the resonator 400. For example, the
matcher 430 includes a conductor 431 in a location separate from
the ground conducting portion 413 by a distance h. Adjusting the
distance h changes the impedance of the resonator 400.
[0116] Although not illustrated in FIG. 4, a controller may control
the matcher 430. For example, the physical shape of the matcher 430
may be changed based on a control signal generated by the
controller. For example, the control signal may increase or
decrease the distance h between the conductor 431 of the matcher
430 and the ground conducting portion 413. Accordingly, the
physical shape of the matcher 430 may be changed to adjust the
impedance of the resonator 400. The distance h between the
conductor 431 and the ground conducting portion 413 may be adjusted
using a variety of schemes. As one example, the matcher 430 may
include a plurality of conductors, and the distance h may be
adjusted by adaptively activating one of the conductors. As another
example, adjusting the physical location of the conductor 431 up
and down may adjust the distance h. The distance h may be
controlled based on the control signal of the controller. The
controller may generate the control signal using various
factors.
[0117] As shown in FIG. 4, the matcher 430 is configured as a
passive element, such as the conductor 431. Depending on examples,
the matcher 430 may be configured as an active element. The active
element may be a diode, a transistor, and/or the like. In response
to the active element being included in the matcher 430, the active
element may be driven based on the control signal generated by the
controller, and the impedance of the resonator 400 may be adjusted
based on the control signal. For example, a diode may be included
in the matcher 430, where the diode is a type of active element.
For example, the impedance of the resonator 400 may be adjusted
based on whether the state of the diode is in an ON state or an OFF
state.
[0118] Although not illustrated in FIG. 4, a magnetic core may be
provided to pass through the resonator 400 configured as the MNG
resonator. The magnetic core may increase a power transmission
distance.
[0119] FIG. 5 illustrates an example of a bulky-type resonator 500
for wireless power transmission. A first signal conducting portion
511 and a second signal conducting portion 512 is integrally
formed, instead of being separately manufactured and thereafter
connected to each other. A capacitor 520 is inserted in a space
between the integrally-formed first signal conducting portion 511
and the second signal conducting portion 512.
[0120] As another example, the second signal conducting portion 512
and a conductor 541 are integrally manufactured. When the second
signal conducting portion 512 and the conductor 541 are separately
manufactured and then connected to each other, a loss of conduction
may occur at seam 550. In FIG. 5, the second signal conducting
portion 512 and the conductor 541 are connected to each other
without using a separate seam. In other words, the second signal
conducting portion 512 and the conductor 541 are seamlessly
connected to each other. Accordingly, a conductor loss caused by
the seam 550 is decreased.
[0121] As another example, the first signal conducting portion 511
and the conductor 542 are integrally manufactured, and the second
signal conducting portion 512 and a ground conducting portion 513
(e.g., including a matcher 530) are seamlessly and integrally
manufactured. As yet another example, the first signal conducting
portion 511 and the ground conducting portion 513 are seamlessly
and integrally manufactured. Referring to FIG. 5, a type of a
seamless connection connecting at least two partitions into an
integrated form may be referred to as a bulky-type.
[0122] FIG. 6 illustrates an example of a hollow-type resonator 600
for wireless power transmission. Each of a first signal conducting
portion 611, a second signal conducting portion 612, a ground
conducting portion 613 (including a matcher 630), and conductors
641 and 642 of the hollow-type resonator 600, includes an empty or
hollow space inside. A capacitor 620 is placed in a portion 660
between the first signal conducting portion 611 and the second
signal conducting portion 612.
[0123] For a given resonance frequency, an active current may be
modeled to flow in only a portion of the first signal conducting
portion 611 instead of the entire first signal conducting portion
611, in only a portion of the second signal conducting portion 612
instead of the entire second signal conducting portion 612, in only
a portion of the ground conducting portion 613 instead of the
entire ground conducting portion 613, in only a portion of the
conductors 641 and 642 instead of the entire conductors 641 and
642, or in any combination thereof. For example, in response to a
depth of each of the first signal conducting portion 611, the
second signal conducting portion 612, the ground conducting portion
613, and the conductors 641 and 642 being significantly deeper than
a corresponding skin depth in the given resonance frequency, the
hollow-type resonator 600 may be ineffective. As a result, the
significantly deeper depth may increase a weight or manufacturing
costs of the resonator 600.
[0124] Accordingly, for the given resonance frequency, the depth of
each of the first signal conducting portion 611, the second signal
conducting portion 612, the ground conducting portion 613, and the
conductors 641 and 642 is determined based on the corresponding
skin depth of each of the first signal conducting portion 611, the
second signal conducting portion 612, the ground conducting portion
613, and the conductors 641 and 642. In response to each of the
first signal conducting portion 611, the second signal conducting
portion 612, the ground conducting portion 613, and the conductors
641 and 642 having an appropriate depth deeper than a corresponding
skin depth, the resonator 600 is lighter in weight, and
manufacturing costs of the resonator 600 may also decrease.
[0125] For example, as shown in the portion 660, the depth of the
second signal conducting
portion 612 is d mm, and d is calculated according to
d = 1 .pi. f .mu. .sigma. . ##EQU00001##
In this example, f corresponds with a resonance frequency, .mu.
corresponds with a magnetic permeability, and .sigma. corresponds
with a conductor constant (e.g., conductivity), of a corresponding
conducting portion. For example, in response to the first signal
conducting portion 611, the second signal conducting portion 612,
the ground conducting portion 613, and the conductors 641 and 642
being made of copper having a magnetic permeability of
1.257.times.10.sup.-6 henries per meter (Hm.sup.-1) and a
conductivity of 5.8.times.10.sup.7 siemens per meter (Sm.sup.-1),
the skin depth may be about 0.6 mm with respect to 10 kHz of the
resonance frequency, and the skin depth may be about 0.006 mm with
respect to 100 MHz of the resonance frequency. These values are
merely examples, and other values may be used depending on the
situation.
[0126] FIG. 7 illustrates a resonator 700 for wireless power
transmission using a parallel-sheet. The parallel-sheet is applied
to each of a first signal conducting portion 711 and a second
signal conducting portion 712 included in the resonator 700. The
resonator 700 further includes a ground conducting portion 713, a
capacitor 720 disposed in a portion 770 between the first signal
conducting portion 711 and the second signal conducting portion
712, and a matcher 730 disposed on the ground conducting portion
713.
[0127] Each of the first signal conducting portion 711 and the
second signal conducting portion 712 may have a resistance. Thus,
the first signal conducting portion 711 and the second signal
conducting portion 712 may not be a perfect conductor. Due to the
resistance, an ohmic loss may occur, which may decrease a Q-factor
and also a coupling effect of the resonator 700.
[0128] By applying the parallel-sheet to each of the first signal
conducting portion 711 and the second signal conducting portion
712, a decrease in the ohmic loss, and an increase in the Q-factor
and the coupling effect is possible. Referring to the portion 770
indicated by a circle, in response to the parallel-sheet being
applied, each of the first signal conducting portion 711 and the
second signal conducting portion 712 includes a plurality of
conductor lines. For example, the plurality of conductor lines are
disposed in parallel, and are connected at an end portion of each
of the first signal conducting portion 711 and the second signal
conducting portion 712. Accordingly, a sum of resistances having
the conductor lines is decreased. In addition, the resistance loss
decreases, and the Q-factor and the coupling effect increases.
[0129] FIG. 8 illustrates an example of a resonator 800 for
wireless power transmission that includes a distributed capacitor
820. A capacitor as a lumped element may have a relatively high
equivalent series resistance (ESR). An ohmic loss caused by the ESR
may decrease a Q-factor and a coupling effect of a resonator. A
variety of schemes have been proposed to decrease the ESR included
in the capacitor of the lumped element. According to an example, by
using the capacitor 820 as a distributed element, a decrease in the
ESR is possible.
[0130] In more detail, the capacitor 820 has a zigzagged structure.
For example, the capacitor 820 as the distributed element is
configured as a conductive line and a conductor having the
zigzagged structure. Employing the capacitor 820 as the distributed
element causes a decrease in the loss occurring due to the ESR.
[0131] In addition, by disposing a plurality of capacitors as
lumped elements, a decrease in the loss occurring due to the ESR
may be possible. Because a resistance of each of the capacitors as
the lumped elements decreases through a parallel connection, active
resistances of parallel-connected capacitors as the lumped elements
may also decrease. Thus, the loss occurring due to the ESR may
decrease. For example, employing ten capacitors of 1 picofarads
(pF) instead of using a single capacitor of 10 pF, may decrease the
loss occurring due to the ESR.
[0132] FIG. 9 illustrates an example of an equivalent circuit of
the resonator for wireless power transmission of FIG. 3. The
resonator of FIG. 3 may be modeled to the equivalent circuit of
FIG. 9. In the equivalent circuit of FIG. 9, C.sub.L corresponds to
a capacitor that is inserted in the form of a lumped element at
approximately the middle of one of the transmission lines of FIG.
3.
[0133] In this example, the resonator of FIG. 3 may have a zeroth
resonance characteristic. For example, in response to a propagation
constant being "0", the resonator of FIG. 3 may have
.omega..sub.MZR as a resonance frequency. The resonance frequency
.omega..sub.MZR is expressed by Equation 1.
.omega. MZR = 1 L R C L [ Equation 1 ] ##EQU00002##
[0134] In Equation 1, MZR corresponds to a Mu zero resonator. The
capacitance C.sub.R of the resonator is negligible compared to the
capacitance C.sub.L of the lumped element capacitor, so it is
omitted from Equation 2. The resonance frequency .omega..sub.MZR of
the resonator of FIG. 3 depends on L.sub.RC.sub.L. A physical size
of the resonator of FIG. 3 and the resonance frequency
.omega..sup.MZR may be independent of each other. Because the
physical size and the resonance frequency are independent with
respect to each other, the physical size of the resonator of FIG. 3
may be sufficiently reduced.
[0135] FIG. 10 illustrates an example of a rectification system
1000 of a wireless power receiver. The rectification system 1000
includes a target resonator 1010, a rectifier 1020, a capacitor
1030, and a DC/DC converter 1040.
[0136] The target resonator 1010 receives a radio frequency (RF)
power. The rectifier 1020 rectifies the received RF power. The
rectifier 1020 may include, for example, a rectifier diode and/or
the like.
[0137] The capacitor 1030 stores the power rectified by the
rectifier 1020. That is, the rectifier 1020 and the capacitor 1030
convert the received RF power to a DC power.
[0138] The converted DC power is input into the DC/DC converter
1040. An input voltage (V.sub.in) refers to a level of the
converted DC power that is input into the DC/DC converter 1040.
[0139] The DC/DC converter 1040 converts the input voltage V.sub.in
to an output voltage (V.sub.out). A voltage level of the output
voltage V.sub.out may correspond to +5 volts (V). Here, +5V is
provided as an example, and may refer to a level of a voltage
requested by a load 1050.
[0140] The DC/DC converter 1040 supplies a power corresponding to a
voltage level of the converted DC power to the load 1050. The load
1050 may correspond to a battery. The load 1050 includes a charger
circuit, a protection circuit module (PCM), and a battery cell.
[0141] A high voltage may be applied to the rectifier 1020 and/or
the capacitor 1030 of the rectification system 1000. In addition,
the wireless power transmission may employ a resonance scheme using
a band of 1 MHz to 15 MHz.
[0142] In order to design the rectifier 1020 with a high efficiency
in the band of 1 MHz to 15 MHz, the rectifier 1020 may include a
Schottky diode. The Schottky diode may have characteristics of a
low voltage drop and a fast recovery time. Performance of the
Schottky diode may be constrained by a size of the Schottky diode.
Consequently, a constraint on an available voltage and current may
occur due to the size constraint. For example, when the Schottky
diode is used for an application for a mobile device, the Schottky
diode may have a size applicable to the mobile device, and a
general-purpose Schottky diode having an allowable current of 1
ampere (A) and a voltage drop less than or equal to 0.5 V may have
a peak reverse voltage between 20 V and 30 V. As used herein, the
term "peak reverse voltage" may be interchangeable with a term
"peak-inverse-voltage".
[0143] A peak reverse voltage may refer to a maximum voltage that
may be applied to a device in a reverse direction. When a voltage
applied to the Schottky diode exceeds the peak reverse voltage, the
Schottky diode may be damaged. Accordingly, there is a demand for a
protection circuit that may protect the Schottky diode so that
voltages applied to an input end and an output end of the rectifier
1020 may not exceed the peak reverse voltage of the Schottky
diode.
[0144] FIG. 11 illustrates an example of a battery 1100. The
battery 1100 may correspond to the load 1050 of FIG. 10. The
battery 1100 includes a charger circuit 1110, a PCM 1120, and a
battery cell 1130.
[0145] The charging circuit 1110 adjusts a level of a charging
voltage and a level of a charging current based on a charging stage
of the battery 1100, for a stable charging operation of the battery
1100. The battery 1100 has a configuration in which a power is
transferred to the charger circuit 1110, and then transferred to
the PCM 1120 and the battery cell 1130.
[0146] The PCM 1120 protects the battery 1100 from an overvoltage,
an over-discharge, an overcurrent, and/or the like. The battery
cell 1130 charges a current.
[0147] In more detail, the PCM includes a field-effect transistor
(FET) switch 1122 and a protection circuit 1124. The FET switch
1122 includes a switch between a power provided from an external
environment and the battery cell 1130. When the FET switch 1122 is
closed, the power provided from the external environment is
transferred to the battery cell 1130, and the battery 1100 is
charged.
[0148] The protection circuit 1124 senses a voltage, a current,
and/or the like, applied to the battery 1100. When an overvoltage,
an over-discharge, an overcurrent, and/or the like is detected, the
protection circuit 1124 blocks the FET switch 1122 from
transferring power to the battery cell 1130, thereby enabling the
battery 1100 to be in an open state to protect the battery cell
1130.
[0149] FIG. 12 illustrates an example of a charging graph of a
battery according to a charging time. The battery 1100 of FIG. 11
may correspond to a battery of a mobile device. The graph of FIG.
12 may correspond to a charging graph of a battery for a mobile
device.
[0150] For example, a constant current of about 600 milli amperes
(mA) flows from an initial state in which the battery 1100 of FIG.
11 is initiated to be charged, to a state in which the battery 1100
is charged up to about 80% of capacity. That is, a period from the
initial state in which the battery 1100 is initiated to be charged,
to the state in which the battery 1100 is charged up to about 80%
of capacity, may be regarded as a current limit period. In this
example, an output voltage corresponding to a cell voltage of the
battery cell 1130 is increased from 2.5 V to 4.2 V.
[0151] After the battery 1100 is charged up to about 80% of
capacity, the output voltage of the battery cell 1130 is a constant
voltage of 4.2 V, and an amount of a current used to charge the
battery 1100 (e.g., a charge rate), is gradually reduced. A period
after the battery 1100 is charged up to about 80% of capacity, may
be regarded as a constant voltage period.
[0152] When the battery 1100 is fully charged, that is, in a full
charging state, the PCM 1120 or the FET switch 1122 of FIG. 11 is
disconnected from a power supply, and the battery 1100 is in an
open state. That is, a voltage of the battery 1100 is constant, and
the amount of the current used to charge the battery 1100 is
reduced during a period from when the charging state of the battery
1100 corresponds to about 80% of capacity, to when the charging
state of the battery 1100 is close to 100% of capacity, that is, a
full charging state. Accordingly, an impedance of a load (e.g., the
battery 1100) is gradually increased from 10 ohms (.OMEGA.) to 20
.OMEGA., 50.OMEGA., and 100.OMEGA., based on Equation 2.
Z.sub.load=V.sub.load/I.sub.load [Equation 2]
[0153] where Z.sub.load denotes the impedance of the load,
V.sub.load denotes a voltage of the load, and l.sub.load denotes a
current of the load.
[0154] When the PCM 1120 of the battery 1100 is operated, the
impedance of the load corresponds to an open load, that is, a few
kilo-ohms (k.OMEGA.).
[0155] FIGS. 13 through 15 illustrate examples of results of
simulations of magnitudes of voltages applied, respectively, to a
front end (e.g., an input end) and a back end (e.g., an output end)
of a rectifier, using an Advanced Design System (ADS) tool, when an
impedance of a load is changed from 10.OMEGA. to 100.OMEGA. to 1
k.OMEGA.. With reference to FIGS. 13 through 15, a change in a
voltage level based on an impedance when a battery load for a
mobile device is charged, will be described. Each block shown in
FIGS. 13 through 15 may be modeled to correspond to a device that
may be used in reality.
[0156] FIG. 13 illustrates an example of results of a simulation of
magnitudes of voltages applied, respectively, to a front end and a
back end of a rectifier when an impedance of a load corresponds to
10.OMEGA.. In more detail, FIG. 13 shows simulation results when an
impedance Z.sub.load of a load corresponds to 10.OMEGA., that is,
with respect to a period during which the battery 1100 of FIG. 11
is normally charged.
[0157] For example, a power output from a power amplifier (PA) is
4.6 W. However, due to improper matching of output impedances, a
power output to a source resonator (e.g., P_TX_Watts) is reduced to
4.09 W.
[0158] When an efficiency in a case in which a power passes through
a target resonator, a matching circuit, and the rectifier (e.g.,
Effi_Resonator_Rectifier), is about 74.98%, and a power (e.g.,
P_Load_Watts) of about 3 W is transferred to the load. A
peak-to-peak voltage of 12.895 V is applied to the front end of the
rectifier, and a DC voltage of 5.539 V is applied to the back end
of the rectifier.
[0159] Accordingly, in a normal charging period, a power is
transferred efficiently without burdening the rectifier. The normal
charging period may correspond to a constant current mode in which
a constant current flows through the load.
[0160] FIG. 14 illustrates an example of results of a simulation of
magnitudes of voltages applied, respectively, to a front end and a
back end of a rectifier when an impedance of a load corresponds to
100.OMEGA.. In more detail, FIG. 14 shows simulation results when
an impedance Z.sub.load of a load corresponds to 100.OMEGA., that
is, with respect to a period during which a charging state of the
battery 1100 of FIG. 11 is getting closer to a full charging state.
The period during which the charging state of the battery 1100 is
getting closer to the full charging state may correspond to a
constant voltage mode in which a constant voltage is applied to the
load.
[0161] For example, a power output from a PA is 4.6 W. However, due
to improper matching of output impedances, a power output to a
source resonator is reduced to 2.5 W.
[0162] An efficiency in a case in which a power passes through a
target resonator, a matching circuit, and the rectifier, is about
73.86%. A power of 1.851 W is transferred to the load. Since the
impedance of the load is relatively large in value, a peak-to-peak
voltage of 28.449 V is applied to the front end of the rectifier,
and a DC voltage of 13.6 V is applied to the back end of the
rectifier, when a relatively low amount of power is transferred to
the load. That is, the voltage applied to the front end of the
rectifier becomes close to a peak reverse voltage of a Schottky
diode, e.g., 30 V.
[0163] FIG. 15 illustrates an example of results of a simulation of
magnitudes of voltages applied, respectively, to a front end and a
back end of a rectifier when an impedance of a load corresponds to
1 k.OMEGA.. In more detail, FIG. 15 illustrates simulation results
when an impedance Z.sub.load of a load corresponds to 1 k.OMEGA.,
that is, with respect to a period during which the battery 1100 of
FIG. 11 is fully charged.
[0164] For example, a power output from a PA is 4.6 W. However, due
to improper matching of output impedances, a power output to a
source resonator is reduced to 1.173 W.
[0165] An efficiency in a case in which a power passes through a
target resonator, a matching circuit, and the rectifier is about
31.48%. A power of 0.369 W is transferred to the load. Since the
impedance of the load is relatively great, a peak-to-peak voltage
of 40.5 V is applied to the front end of the rectifier, and a DC
voltage of 19.2 V is applied to the back end of the rectifier, when
a relatively less power is transferred to the load. When the
aforementioned voltages are applied to the front end and the back
end of the rectifier, and a Schottky diode used in the rectifier
has a peak reverse voltage of 30 V, the Schottky diode may be
damaged.
[0166] Output impedance matching of the PA, which may be set to
50.OMEGA., may more match an impedance Z.sub.load in an actual
experimental environment. When the output impedance matching of the
PA more matches the impedance Z.sub.load, a magnitude of a power to
be transferred to a resonator may increase. Accordingly, voltages
greater than the voltages shown in the simulation results, may be
applied to both ends of the rectifier.
[0167] In an application of an electric vehicle that may transmit a
wireless power of a few kW, a change in a voltage applied to the
rectifier, when the impedance Z.sub.load is changed depending on a
charging state of the load, may be similar to the descriptions
provided with reference to FIGS. 13 through 15. In addition, a
voltage level in the application of the electric vehicle may be
much greater than a voltage level in an application for a mobile
device. Accordingly, in order to charge a load (e.g., a battery)
wirelessly and efficiently, there is a demand for a circuit that
may protect a rectifier or a power receiver.
[0168] As can be understood from FIGS. 13 through 15, when a
resonance-type wireless power transmission is used, a level of an
input voltage of a DC/DC converter may be determined based on a
state of an impedance of a load. Accordingly, as a charging state
of the load approaches a full charging state, the impedance of the
load may increase, and the rectifier and/or the like of the
wireless power receiver may be damaged due to an overvoltage caused
by the increased impedance of the load.
[0169] FIG. 16 illustrates an example of a wireless power receiver
1600 including a short-type protection circuit. The wireless power
receiver 1600 may correspond to a wireless power receiver for a
mobile application having a band of a few MHz. The wireless power
receiver 1600 includes a resonator 1610, a matching circuit 1615, a
rectifier 1620, a capacitor 1625, and a DC/DC converter 1630. The
wireless power receiver 1600 further includes a load 1690.
[0170] The resonator 1610 may correspond to the target resonator
1010 of FIG. 10. The resonator 1610 provides a received power to
the rectifier 1620 through the matching circuit 1615.
[0171] The matching circuit 1615 may include an impedance matching
circuit. The rectifier 1620 may correspond to the rectifier 1020 of
FIG. 10. The capacitor 1625 may correspond to the capacitor 1030 of
FIG. 10. The DC/DC converter 1630 may correspond to the DC/DC
converter 1040 of FIG. 10. The load 1690 may correspond to the load
1050 of FIG. 10.
[0172] The wireless power receiver 1600 further includes a first
varistor 1640 and a second varistor 1650. Here, the first varistor
1640 and the second varistor 1650 are provided as examples. Each of
the first varistor 1640 and the second varistor 1650 may be
replaced with a predetermined device that may create a short
circuit when a voltage greater than a threshold voltage is
applied.
[0173] The rectifier 1620 outputs a rectified signal through an
output end by rectifying a signal received by the resonator 1610.
The capacitor 1625 is connected to the output end of the rectifier
1620 and ground.
[0174] The DC/DC converter 1630 is connected to the output end of
the rectifier 1620 and the load 1690. The DC/DC converter 1630
converts the rectified signal, and provides a converted power to
the load 1690. The DC/DC converter 1630 may include a DC/DC buck
converter.
[0175] The first varistor 1640 and the second varistor 1650 create
a short circuit when a voltage greater than the threshold voltage
is applied. For example, the first varistor 1640 create a short
circuit when a voltage greater than a first threshold voltage is
applied to an input end of the rectifier 1620. The second varistor
1650 create a short circuit when a voltage greater than a second
threshold voltage is applied to the output end of the rectifier
1620.
[0176] For example, in the mobile application using the band of a
few MHz, the wireless power receiver 1600 protects the rectifier
1620 and/or the capacitor 1625, using the first varistor 1640 and
the second varistor 1650. In this example, when the first varistor
1640 creates a short circuit before a voltage greater than a peak
voltage of the rectifier 1620 is applied to the rectifier 1620, a
voltage applied to the rectifier 1620 is reduced, and an impedance
of the rectifier 1620 is changed, whereby a power received by the
rectifier 1620 is reduced. That is, when the first varistor 1640
creates a short circuit, the rectifier 1620, or a Schottky diode
included in the rectifier 1620, is protected. The first varistor
1640 may include a varistor for RF.
[0177] Also, when the second varistor 1650 creates a short circuit
before a voltage greater than a peak voltage of the capacitor 1625
is applied to the capacitor 1625, a voltage applied to the
capacitor 1625 is reduced, and an impedance of the capacitor 1625
is changed, whereby a power received by the capacitor 1625 is
reduced. That is, when the second varistor 1650 creates a short
circuit, the capacitor 1625 is protected. The second varistor 1650
may include a varistor for DC.
[0178] An input signal that is input through both input ends of the
rectifier 1620 may correspond to a differential signal.
Accordingly, the first varistor 1640 is connected in parallel to
both of the input ends of the rectifier 1620.
[0179] The first varistor 1640 should not influence the matching
circuit 1615. Accordingly, the first varistor 1640 may include a
device having a relatively low capacitance. For example, in a
mobile application using a frequency of 13.56 MHz for wireless
power transmission, the capacitance of the first varistor 1640 may
be less than or equal to 50 pF.
[0180] For example, a voltage of about 3 V to about 5 V less than a
peak reverse voltage of the Schottky diode included in the
rectifier 1620, may be used as a breakdown voltage of the first
varistor 1640. In this example, when the peak reverse voltage of
the Schottky diode is 30 V, the breakdown voltage of the first
varistor 1640 may be 27 V. That is, the first varistor 1640 may
include a device having a breakdown voltage of about 27 V.
[0181] In order to protect the capacitor 1625, the second varistor
1650 is connected to the capacitor 1625 in parallel. That is, the
second varistor 1650 is connected to the capacitor 1625 and
ground.
[0182] The second varistor 1650 may be used in a DC area.
Accordingly, a capacitance of the second varistor 1650 may vary. A
breakdown voltage of the second varistor 1650 may be, for example,
18 V. That is, the second varistor 1650 may include a device having
a breakdown voltage of about 18 V.
[0183] FIG. 17 illustrates another example of a wireless power
receiver 1700 including a short-type protection circuit. The
wireless power receiver 1700 may correspond to a wireless power
receiver for a mobile vehicle application using a band of a few
kHz. The wireless power receiver 1700 includes the resonator 1610,
the matching circuit 1615, the rectifier 1620, the capacitor 1625,
and the DC/DC converter 1630. The wireless power receiver 1700
further includes the load 1690.
[0184] The wireless power receiver 1700 further includes a first
surge absorber (SA) 1740 and a second SA 1750, in lieu of the first
varistor 1640 and the second varistor 1650 of the wireless power
receiver 1600 of FIG. 16. The descriptions of the first varistor
1640 and the second varistor 1650, provided with reference to FIG.
16, may be applied to the first SA 1740 and the second SA 1750,
respectively. Here, the first SA 1740 and the second SA 1750 may be
operated at a voltage greater than or equal to hundreds of volts
(V), as devices that create a short circuit when a voltage greater
than a threshold voltage is applied, in order to protect a Schottky
diode of the rectifier 1620. The first SA 1740 may include an SA
for RF, and the second SA 1750 may include an SA for DC.
[0185] For example, an operating frequency of a wireless power
receiver for an electric vehicle application may be relatively low.
Accordingly, the wireless power receiver 1700 may include devices
having identical capacitances as devices for RF and DC, without
distinguishing between a device for RF and a device for DC. A value
of an operating voltage of the device for RF may be, for example,
twice greater than a value of an operating voltage of the device
for DC.
[0186] The aforementioned short-type protection circuit protects
the rectifier 1620, and the Schottky diode included in the
rectifier 1620, from a surge voltage, for example, an electrostatic
discharge (ESD) and/or the like, which may occur in, for example, a
transient period of an initial state and/or the like. However,
although the short-type protection circuit is used, a protective
device may be damaged in a full charging state, or in a state in
which a high impedance may be maintained constantly, for example,
in a constant voltage mode. In order to prevent such damage, an
open-type protection circuit, which will be described later, may be
used in conjunction with the short-type protection circuit.
[0187] FIG. 18 illustrates an example of a wireless power receiver
1800 including an open-type protection circuit. The wireless power
receiver 1800 includes a resonator 1810, a matching circuit 1815, a
rectifier 1820, a capacitor 1825, a DC/DC converter 1830, a switch
unit 1840, and a protection unit 1850. The wireless power receiver
1800 further includes a load 1890.
[0188] The resonator 1810 may correspond to the target resonator
1010 of FIG. 10. The resonator 1810 provides a received power to
the rectifier 1820 through the matching circuit 1815.
[0189] The matching circuit 1815 may include, for example, an
impedance matching circuit. The rectifier 1820 may correspond to
the rectifier 1020 of FIG. 10. The capacitor 1825 may correspond to
the capacitor 1030 of FIG. 10. The DC/DC converter 1830 may
correspond to the DC/DC converter 1040 of FIG. 10. The DC/DC
converter 1830 may include, for example, a buck converter. The load
1890 may correspond to the load 1050 of FIG. 10.
[0190] The rectifier 1820 outputs a rectified signal through an
output end by rectifying a signal received by the resonator 1810.
The capacitor 1825 is connected to the output end of the rectifier
1820 and ground.
[0191] The DC/DC converter 1830 is connected to the output end of
the rectifier 1820 and the load 1890. The DC/DC converter 1830
converts the rectified signal, and provides a converted power to
the load 1890.
[0192] The switch unit 1840 includes two switches, that is, a first
switch 1842 and a second switch 1844. Each of the first switch 1842
and the second switch 1844 may include, for example, a RF
switch.
[0193] Each of the first switch 1842 and the second switch 1844
connect one of both respective input ends of the rectifier 1820 to
the resonator 1810. For example, the first switch 1842 connects a
first input end of the rectifier 1820 to the resonator 1810. The
second switch 1844 connects a second input end of the rectifier
1820 to the resonator 1810.
[0194] Each of the first switch 1842 and the second switch 1844
includes a switch of which an initial condition is to create a
short circuit. As an example, each of the first switch 1842 and the
second switch 1844 may include a p-channel
metal-oxide-semiconductor field-effect transistor (PMOS) switch.
That is, each of the first switch 1842 and the second switch 1844
may include an analog switch having a relatively low insertion
loss, and of which an initial condition is to create a short
circuit. As another example, each of the first switch 1842 and the
second switch 1844 may include an RF PMOS FET. That is, each of the
first switch 1842 and the second switch 1844 may be turned ON, or
create a short circuit, when a control voltage of 0 V is received
or applied, and may be turned OFF, or opened, when a control
voltage of 3.3 V is received or applied. The voltage values
described above are merely examples, and other voltage values may
be used depending on the situation.
[0195] The protection unit 1850 controls the switch unit 1840. In
more detail, the protection unit 1850 controls the switch unit 1840
to be closed or opened, that is, turned ON or turned OFF, based on
a voltage of the rectified signal that is output by the rectifier
1820.
[0196] For example, the switch unit 1840 is connected to a front
end of the rectifier 1820. When a protection circuit of the
protection unit 1850 is operated, the protection unit 1850 opens
the first switch 1842 and the second switch 1844 of the switch unit
1840, thereby protecting the rectifier 1820 and the capacitor 1825.
The open-type protection circuit protects the wireless power
receiver 1800 when the load 1890 is fully charged, or when the
wireless power receiver 1800 is in a constant voltage mode.
[0197] The protection unit 1850 controls the switch unit 1840, that
is, the first switch 1842 and the second switch 1844, to create a
short circuit when the voltage of the rectified signal is less than
a threshold value, or when the voltage of the rectified signal is
less than or equal to the threshold value, thereby enabling the
rectifier 1820 to receive an input of the signal received by the
resonator 1810. The protection unit 1850 controls the switch unit
1840, that is, the first switch 1842 and the second switch 1844, to
be opened when the voltage of the rectified signal is greater than
the threshold value, or when the voltage of the rectified signal is
greater than or equal to the threshold value, thereby blocking,
from the rectifier 1820, the signal received by the resonator
1810.
[0198] The protection unit 1850 outputs a switch control signal.
The switch unit 1840 creates a short circuit or opened based on the
switch control signal.
[0199] While the load 1890 is being charged, the protection unit
1850 outputs the switch control signal to control the switch unit
1840 to close. For example, the switch control signal to control
the switch unit 1840 to close may include a signal that applies a
voltage of 0 V to the switch unit 1840.
[0200] When the load 1890 is fully charged, a protection circuit is
to be operated. Accordingly, the protection unit 1850 outputs the
switch control signal to control the switch unit 1840 to open. For
example, the switch control signal to control the switch unit 1840
to open may include a signal that applies a voltage of 3.3 V to the
switch unit 1840.
[0201] For example, in an initial state in which a control voltage
of 0 V is applied to the switch unit 1840 based on the switch
control signal, that is, when a voltage of the switch control
signal is 0 V, the switch unit 1840 closes the first switch 1842
and the second switch 1844. When the protection circuit is
operated, and a control voltage of 3.3 V is applied to the switch
unit 1840, that is, when the voltage of the switch control signal
is 3.3 V, the switch unit 1840 opens the first switch 1842 and the
second switch 1844.
[0202] Hereinafter, the protection unit 1850 will be described in
detail. The protection unit 1850 includes a voltage adjustor 1860,
a comparator 1870, a first voltage divider 1881, and a second
voltage divider 1885. The first voltage divider 1881 includes a
first resistor 1882 and a second resistor 1884. The second voltage
divider 1885 includes a third resistor 1886 and a fourth resistor
1888.
[0203] The voltage adjustor 1860 is connected to the DC/DC
converter 1830 to receive a converted power that is output by the
DC/DC converter 1830. That is, a voltage to be input to the voltage
adjustor 1860 is extracted from a back end of the DC/DC converter
1830.
[0204] The voltage adjustor 1860 is connected to the comparator
1870 to generate a power source V.sub.dd to operate the comparator
1870, and a first comparator input signal V.sub.ref of the
comparator 1870. The first comparator input signal V.sub.ref
includes a reference voltage of the comparator 1870. For example,
in an application for a mobile device, when a voltage output from
the DC/DC converter 1830 is 5 V, the voltage adjustor 1860 may
convert the output voltage of 5 V to 3.3 V, which is used for the
power source V.sub.dd to operate the comparator 1870, and the first
comparator input signal V.sub.ref. That is, the voltage adjustor
1860 generates the first comparator input signal V.sub.ref by
adjusting the voltage of the converted power that is output by the
DC/DC converter 1830. The voltage adjustor 1860 may include, for
example, a Low Drop Output (LDO) regulator, a bandgap reference
device, and/or the like.
[0205] The first voltage divider 1881 is connected to the output
end of the rectifier 1820 and the comparator 1870. The first
voltage divider 1881 generates a second comparator input signal
V.sub.in2 of the comparator 1870 by dividing a voltage V.sub.in1 of
the rectified signal that is output by the rectifier 1820.
[0206] The first resistor 1882 is connected to a positive (+) input
end of the comparator 1870 and the output end of the rectifier
1820. The second resistor 1884 is connected to the + input end of
the comparator 1870 and ground.
[0207] The first resistor 1882 and the second resistor 1884 divide
an input voltage, that is, the voltage V.sub.in1 of the rectified
signal that is output by the rectifier 1820, by 1/N, and enable the
divided voltage to be output. Here, N corresponds to a real number
greater than or equal to 1. For example, when the input voltage is
divided by 1/3, a resistance of the first resistor 1882 is 2
k.OMEGA., and a resistance of the second resistor 1884 is 1
k.OMEGA..
[0208] By dividing the input voltage, it may be unnecessary to
increase the reference voltage V.sub.ref using an additional boost
converter and/or the like. Also, a single LOD device or a single
bandgap reference device may be used for the power V.sub.dd to
operate the comparator 1870, and the first comparator input signal
V.sub.ref.
[0209] The comparator 1870 outputs a comparator output signal
through an output end, by comparing the first comparator input
signal V.sub.ref and the second comparator input signal V.sub.in2.
For example, when the first comparator input signal V.sub.ref is
higher than the second comparator input signal V.sub.in2, the
comparator 1870 outputs the comparator output signal having a
control voltage to control the switch unit 1840 to close, for
example, a voltage of 0 V. Conversely, when the second comparator
input signal V.sub.in2 is higher than the first comparator input
signal V.sub.ref, the comparator 1870 outputs the comparator output
signal having a control voltage to control the switch unit 1840 to
open, for example, the power V.sub.dd to operate the comparator
1870, or a voltage of 3.3 V.
[0210] The control voltage to control the switch unit 1840 to close
may be referred to as a voltage to turn the switch unit 1840 or the
wireless power receiver 1800 ON, and the control voltage to control
the switch unit 1840 to open may be referred to as a voltage to
turn the switch unit 1840 or the wireless power receiver 1800 OFF.
The comparator 1870 may perform a hysteresis operation for a stable
operation of the wireless power receiver 1800. That is, the
comparator 1870 may set a first voltage to change a state of the
switch unit 1840 from an open state to a closed state, to be
different from a second voltage to change the state of the switch
unit 1840 from the closed state to the open state.
[0211] As an example, when the second comparator input signal
V.sub.in2 is higher than the first comparator input signal
V.sub.ref by a voltage greater than 1 V, the comparator 1870 may
change the comparator output signal from the control voltage to
control the switch unit 1840 to close, to the control voltage to
control the switch unit 1840 to open. Conversely, when the second
comparator input signal V.sub.in2 is less than the first comparator
input signal V.sub.ref by a voltage greater than 1 V, the
comparator 1870 may change the comparator output signal from the
control voltage to control the switch unit 1840 to open, to the
control voltage to control the switch unit 1840 to close.
[0212] As another example, when the voltage V.sub.in1 of the
rectified signal, which will be hereinafter referred to as a
voltage V.sub.in1 to be input to the DC/DC converter 1830, is less
than or equal to 10 V, the second comparator input signal V.sub.in2
may be less than or equal to 3.3 V, through a voltage division of
1/N performed by the first voltage divider 1881. Accordingly, since
the second comparator input signal V.sub.in2 is less than the first
comparator input signal V.sub.ref of 3.3 V, the comparator 1870 may
output the comparator output signal having a voltage of 0 V, or the
control voltage to control the switch unit 1840 to close. The
control voltage to control the switch unit 1840 to close may
correspond to a GND.
[0213] Conversely, when the voltage V.sub.in1 to be input to the
DC/DC converter 1830 is greater than or equal to 10 V, the second
comparator input signal V.sub.in2 may be greater than or equal to
3.3 V, through the voltage division of 1/N performed by the first
voltage divider 1881. Accordingly, since the second comparator
input signal V.sub.in2 is greater than the first comparator input
signal V.sub.ref of 3.3 V, the comparator 1870 may output the
comparator output signal having a voltage of 3.3 V, or the control
voltage to control the switch unit 1840 to open.
[0214] The second voltage divider 1885 outputs a switch control
signal by dividing a voltage of the comparator output signal. The
third resistor 1886 is connected to the switch unit 1840 and the
output end of the comparator 1870. The third resistor 1886 prevents
an overcurrent from flowing through the switch control signal. For
example, when the wireless power receiver 1800 is for an
application for a mobile device, the third resistor 1886 may have a
resistance of 100 .OMEGA..
[0215] The fourth resistor 1888 is connected to the output end of
the comparator 1870 and ground. The fourth resistor 1888 includes a
resistor to maintain the two switches receiving the control voltage
of 0 V, for example, the first switch 1842 and the second switch
1844, to be turned ON during an initial operation of the wireless
power transmission. For example, when the wireless power receiver
1800 is for an application for a mobile device, the fourth resistor
1888 may have a resistance of 10 k.OMEGA.. The protection unit 1850
corresponding to an open-type protection unit may resolve a problem
of damage to the wireless power receiver 1800 resulting from an
operation of a PCM blocking mode when the battery 1100 is fully
charged.
[0216] FIG. 19 illustrates an example of an operation of the
wireless power receiver 1800 of FIG. 18 including an open-type
protection circuit in a normal charging mode. The normal charging
mode may refer to a constant current mode.
[0217] The switch unit 1840 includes a switch of which an initial
condition is to create a short circuit. For example, the switch
unit 1840 may include a PMOS switch for each of the first switch
1842 and the second switch 1844.
[0218] When the wireless power receiver 1800 receives a wireless
power at the beginning, the switch unit 1840 receives, from the
protection unit 1850, a comparator output signal having a control
voltage V.sub.c of 0 V. Accordingly, the switch unit 1840, that is,
the first switch 1842 and the second switch 1844 of the switch unit
1840, may be maintained to be turned ON.
[0219] In an application for a mobile device, an impedance of the
load 1890 is 10.OMEGA. in the normal charging mode. Due to the
impedance of the load 1890, a voltage V.sub.in1 to be input into
the DC/DC converter 1830, does not exceed 10 V.
[0220] The input voltage V.sub.in1 is divided 1/N by the first
resistor 1882 and the second resistor 1884, and a second comparator
input signal V.sub.in2 is generated, which is less than 3.3 V. A
reference voltage of 3.3V is included in a first comparator input
signal V.sub.ref, from the voltage adjustor 1860.
[0221] Since the second comparator input signal V.sub.in2 is less
than the first comparator input signal V.sub.ref, the comparator
1870 outputs a voltage of 0 V corresponding to GND. Accordingly,
the switch unit 1840, that is, the first switch 1842 and the second
switch 1844 of the switch unit 1840, is maintained to be turned
ON.
[0222] FIG. 20 illustrates an example of an operation of the
wireless power receiver 1800 of FIG. 18 including an open-type
protection circuit in a full charging mode. In an application for a
mobile device, an impedance of the load 1890 is considerably
increased when a state of the load 1890 is close to a full charging
state. For example, when the impedance of the load 1890 is close to
1 k.OMEGA., a voltage V.sub.in1 to be input into the DC/DC
converter 1830 exceeds 10 V.
[0223] The input voltage V.sub.in1 is divided by 1/N by the first
resistor 1882 and the second resistor 1884, and a second comparator
input signal V.sub.in2 is generated, which is greater than 3.3 V. A
reference voltage of 3.3V is included in a first comparator input
signal V.sub.ref, from the voltage adjustor 1860.
[0224] Since the second comparator input signal V.sub.in2 is
greater than the first comparator input signal V.sub.ref, the
comparator 1870 outputs a voltage of 3.3 V corresponding to a power
V.sub.dd to operate the comparator 1870. Accordingly, the switch
unit 1840, that is, the first switch 1842 and the second switch
1844 of the switch unit 1840, is turned OFF.
[0225] When the switch unit 1840, that is, the first switch 1842
and the second switch 1844 of the switch unit 1840, is turned OFF,
a power is not input into the rectifier 1820. Accordingly, a power
accumulated in the capacitor 1825 is consumed, and the input
voltage V.sub.in1 is decreased to be less than or equal to 10 V.
When the input voltage V.sub.in1 is controlled to be less than a
predetermined voltage, the rectifier 1820 and/or the like is
protected. When the input voltage V.sub.in1 becomes less than 10 V,
a switch control signal of 0 V is output, and the switch unit 1840,
that is, the first switch 1842 and the second switch 1844 of the
switch unit 1840, is turned ON again. Accordingly, in the full
charging state, operations of turning the switch unit 1840 OFF and
ON is iterated as aforementioned.
[0226] FIG. 21 illustrates an example of operations of a wireless
power transmitter 2100 and the wireless power receiver 1800 in a
full charging mode. In more detail, FIG. 21 describes a method of
sensing a full charging state of the load 1890, and a method of
blocking a power of the wireless power transmitter 2100 through a
communication between the wireless power transmitter 2100 and the
wireless power receiver 1800.
[0227] The wireless power transmitter 2100 includes a signal
generator 2110, a switch 2120, a power amplifier 2130, a source
resonator 2140, and a communication/control unit 2150. The signal
generator 2110 generates a signal for wireless power
transmission.
[0228] The switch 2120 connects or disconnects the signal generator
2110 and the power amplifier 2130. The power amplifier 2130
generates an amplified signal by amplifying the signal generated by
the signal generator 2110.
[0229] The source resonator 2140 transfers, through a resonance,
the amplified signal to a target resonator 2160 of the wireless
power receiver 1800. The communication/control unit 2150 controls
the switch 2120 and the power amplifier 2130 based on a signal
transmitted from a communication/control unit 2170 of the wireless
power receiver 1800. The communication/control unit 2150 may
include, for example, a Micro Controller Unit (MCU).
[0230] The wireless power receiver 1800 includes the target
resonator 2160 and the communication/control unit 2170. The target
resonator 2160 may include, for example, a matching circuit (not
shown). The target resonator 2160 generates a signal by receiving
the power transmitted from the wireless power transmitter 2100.
[0231] The communication/control unit 2170 receives a switch
control signal from the protection unit 1850. The
communication/control unit 2170 transmits, based on the received
switch control signal, a power transmission suspension signal to
the wireless power transmitter 2100. The power transmission
suspension signal may include a signal requesting suspension of
power transmission.
[0232] When the load 1890 is fully charged, and an impedance of the
load 1890 is constantly maintained to be a few k.OMEGA.
corresponding to a full charging impedance, an input voltage
V.sub.in1 is greater than 10 V. Accordingly, the protection unit
1850 generates a switch control signal having a high control
voltage of 3.3 V, thereby turning OFF two switches (not shown) of
the switch unit 1840.
[0233] When the two switches are turned OFF, a power to be supplied
to the rectifier 1820 is blocked, and a power accumulated in a
capacitor (not shown) is consumed, whereby the input voltage
V.sub.in1 becomes less than 10 V. Here, the capacitor may
correspond to the capacitor 1825 of FIG. 18. When the input voltage
V.sub.in1 becomes less than 10 V, the protection unit 1850
generates a switch control signal having a low control voltage of 0
V, and the two switches of the switch unit 1840 are turned ON based
on the switch control signal.
[0234] When the above-described process of turning the switch unit
1840 ON and OFF is iterated, an output wave pattern of the control
voltage of the switch control signal, in which a low control
voltage and a high control voltage are iterated, is generated in a
full charging area. For example, when the control voltage of the
switch control signal is changed to the low control voltage and the
high control voltage, iteratively, the communication/control unit
2170 counts a number of times the control voltage of the switch
control signal is changed. When the number of times the control
voltage of the switch control signal is changed corresponds to N,
the communication/control unit 2170 senses a full charging state of
the wireless power receiver 1800, and transmits a power
transmission suspension signal to the wireless power transmitter
2100. Here, N may be, for example, an integer greater than or equal
to 1. The value of N may be predetermined through an
experiment.
[0235] That is, the communication/control unit 2170 transmits the
power transmission suspension signal when the received switch
control signal is changed, N number of times, between a signal
indicating that the load 1890 is being charged (e.g., a low control
voltage of 0 V), and a signal indicating that the load 1890 is
fully charged (e.g., a high control voltage of 3.3 V). When the
wireless power transmitter 2100 suspends the power transmission,
the charging process is completed.
[0236] The wireless power transmitter 2100 and the wireless power
receiver 1800 may perform an in-band communication in which a power
supply frequency corresponds to a communication frequency. In
addition, the wireless power transmitter 2100 and the wireless
power receiver 1800 may perform an out-band communication in which
the power supply frequency is different from the communication
frequency.
[0237] When a method in which the communication/control unit 2170
recognizes a full charging state by counting an N number of times,
is used, a case in which the protection unit 1850 is operated in a
transient area of the beginning of the charging process, that is, a
case in which the protection unit 1850 outputs a switch control
signal to turn the two switches OFF, may not be recognized as a
full charging state. Also, in this method, a case in which the
protection unit 1850 is temporarily operated due to a transient
surge voltage and/or the like, may not be recognized as a full
charging state. In both of these cases, the wireless power
transmitter 2100 may constantly transmit the power.
[0238] As described above, the wireless power receiver 1800 may
sense the full charging state by counting an N number of times a
control voltage is changed. Thus, the wireless power receiver 1800
may distinguish between 1) conversion of the control voltage in a
transient period, and 2) the control voltage due to the transient
surge voltage. The wireless power receiver 1800 may not be required
to use a separate current sensor, and/or the like, to sense the
full charging state.
[0239] When a battery (not shown) is fully charged, a wireless
charging operation may be completed by suspending the power
transmission of the wireless power transmitter 2100 through
communication. Accordingly, the wireless power transmitter 2100 may
be protected as well. By adding the protection unit 1850 and the
communication/control unit 2170 to the wireless power receiver
1800, the wireless power receiver 1800 may be applied to the
battery including an existing PCM (not shown), may act as a
protection circuit, and may sense a full charging state,
simultaneously.
[0240] FIG. 22 illustrates an example of a method of receiving a
wireless power. The method of FIG. 22 may be performed by the
wireless power receiver 1800 of FIG. 21.
[0241] At step 2210, the switch unit 1840 provides or blocks a
received signal from the target resonator 2160. In more detail, the
switch unit 1840 provides, to the rectifier 1820, the received
signal, or blocks, from the rectifier 1820, the received signal,
based on a switch control signal outputted from the protection unit
1850.
[0242] At step 2220, the rectifier 1820 outputs a rectified signal
through an output end, by rectifying the received signal from the
target resonator 2160. The output end of the rectifier 1820 is
connected to one end of a capacitor. Another end of the capacitor
is connected to ground. Here, the capacitor may correspond to the
capacitor 1825 of FIG. 18.
[0243] At step 2230, the DC/DC converter 1830, which is connected
to the output end of the rectifier 1820 and the load 1890,
generates a converted power by converting the rectified signal, and
provides the converted power to the load 1890. At step 2240, the
protection unit 1850 outputs the switch control signal to close or
open the switch unit 1840, based on a voltage of the converted
power and a voltage of the rectified signal.
[0244] In more detail, step 2240 includes steps 2242, 2244, 2246,
and 2248. At step 2242, a voltage adjustor (not shown) of the
protection unit 1850 generates a first comparator input signal by
adjusting a voltage of the converted power.
[0245] At step 2244, a first voltage divider (not shown) of the
protection unit 1850 generates a second comparator input signal by
dividing a voltage of a rectified signal. At step 2246, a
comparator (not shown) of the protection unit 1850 compares the
first comparator input signal and the second comparator input
signal to output a comparator output signal through an output end
of the comparator.
[0246] At step 2248, a second voltage divider (not shown) of the
protection unit 1850 generates a switch control signal to control
(e.g., close or open) the switch unit 1840, by dividing a voltage
of the comparator output signal. Here, the voltage adjustor, the
first voltage divider, the comparator, and the second voltage
divider may correspond to the voltage adjustor 1860, the first
voltage divider 1881, the comparator 1870, and the second voltage
divider 1885 of FIG. 18, respectively.
[0247] At step 2250, the communication/control unit 2170 determines
whether to transmit, to the wireless power transmitter 2100 of FIG.
21, a power transmission suspension signal. For example, the
communication/control unit 2170 receives the switch control signal
from the protection unit 1850, and transmits the power transmission
suspension signal to the wireless power transmitter 2100, based on
the received switch control signal.
[0248] In more detail, step 2250 includes steps 2252, 2254, and
2256. In 2252, the communication/control unit 2170 counts a number
of times the switch control signal is changed between a signal
indicating that the load 1890 is being charged, and a signal
indicating that the load 1890 is fully charged.
[0249] At step 2254, the communication/control unit 2170 verifies
whether the number of times the switch control signal is changed,
is greater than or equal to an N number of times. If the number of
times is greater than or equal to the N number of times, the method
continues at step 2256. Otherwise, the method ends. At step 2256,
the communication/control unit 2170 transmits the power
transmission suspension signal to the wireless power transmitter
2100, which suspends power transmission accordingly.
[0250] The descriptions provided with reference to FIGS. 1 through
21 may be applied to the method of FIG. 22, and thus, detailed
descriptions will be omitted for conciseness. The descriptions
provided with reference to FIGS. 1 through 22 according to the
examples may be applied to a predetermined resonance-type wireless
power receiver, irrespective of a level of power. For example, the
descriptions provided with reference to FIGS. 1 through 22 may be
applied to an electric vehicle using a power of a high level.
[0251] FIG. 23 illustrates an example of an electric vehicle
charging system.
[0252] Referring to FIG. 23, an electric vehicle charging system
2300 includes a source system 2310, a source resonator 2320, a
target resonator 2330, a target system 2340, and an electric
vehicle battery 2350.
[0253] The electric vehicle charging system 2300 may have a similar
structure to the wireless power transmission and charging system of
FIG. 1. The source system 2310 and the source resonator 2320 in the
electric vehicle charging system 2300 may function as a source.
Additionally, the target resonator 2330 and the target system 2340
in the electric vehicle charging system 2300 may function as a
target.
[0254] The source system 2310 may include an AC/DC converter, a
power detector, a power converter, a control/communication unit,
similarly to the source device 110 of FIG. 1. The target system
2340 may include a rectification unit, a DC/DC converter, a switch
unit, a charging unit, and a control/communication unit, similarly
to the target device 120 of FIG. 1.
[0255] The electric vehicle battery 2350 may be charged by the
target system 2340.
[0256] The electric vehicle charging system 2300 may use a resonant
frequency in a band of a few kilohertz (KHz) to tens of MHz.
[0257] The source system 2310 may generate power, based on a type
of charging vehicle, a capacity of a battery, and a charging state
of a battery, and may supply the generated power to the target
system 2340.
[0258] The source system 2310 may control the source resonator 2320
and the target resonator 2330 to be aligned. For example, when the
source resonator 2320 and the target resonator 2330 are not
aligned, the control/communication unit of the source system 2310
may transmit a message to the target system 2340, and may control
alignment between the source resonator 2320 and the target
resonator 2330.
[0259] For example, when the target resonator 2330 is not located
in a position enabling maximum magnetic resonance, the source
resonator 2320 and the target resonator 2330 may not be aligned.
When a vehicle does not stop accurately, the source system 2310 may
induce a position of the vehicle to be adjusted, and may control
the source resonator 2320 and the target resonator 2330 to be
aligned.
[0260] The source system 2310 and the target system 2340 may
transmit or receive an ID of a vehicle, or may exchange various
messages, through communication.
[0261] The descriptions of FIGS. 2 through 22 may be applied to the
electric vehicle charging system 2300. However, the electric
vehicle charging system 2300 may use a resonant frequency in a band
of a few KHz to tens of MHz, and may transmit power that is equal
to or higher than tens of watts to charge the electric vehicle
battery 2350.
[0262] FIGS. 24A through 24B illustrate examples of applications in
which a wireless power receiver and a wireless power transmitter
may be mounted.
[0263] FIG. 24A illustrates an example of wireless power charging
between a pad 2410 and a mobile terminal 2420, and FIG. 24B
illustrates an example of wireless power charging between pads 2430
and 2440 and hearing aids 2450 and 2460.
[0264] In an example, a wireless power transmitter may be mounted
in the pad 2410, and a wireless power receiver may be mounted in
the mobile terminal 2420. The pad 2410 may be used to charge a
single mobile terminal, namely the mobile terminal 2420.
[0265] In another example, two wireless power transmitters may be
respectively mounted in the pads 2430 and 2440. The hearing aids
2450 and 2460 may be used for a left ear and a right ear,
respectively. In this example, two wireless power receivers may be
respectively mounted in the hearing aids 2450 and 2460.
[0266] FIG. 25A illustrates an example of wireless power charging
between an electronic device 2510 that is inserted into a human
body, and a mobile terminal 2520. FIG. 25B illustrates an example
of wireless power charging between a hearing aid 2530 and a mobile
terminal 2540.
[0267] In an example, a wireless power transmitter and a wireless
power receiver may be mounted in the mobile terminal 2520. In this
example, another wireless power receiver may be mounted in the
electronic device 2510. The electronic device 2510 may be charged
by receiving power from the mobile terminal 2520.
[0268] In another example, a wireless power transmitter and a
wireless power receiver may be mounted in the mobile terminal 2540.
In this example, another wireless power receiver may be mounted in
the hearing aid 2530. The hearing aid 2530 may be charged by
receiving power from the mobile terminal 2540. Low-power electronic
devices, for example Bluetooth earphones, may also be charged by
receiving power from the mobile terminal 2540.
[0269] FIG. 26 illustrates an example of a wireless power
transmitter and a wireless power receiver.
[0270] In FIG. 26, a wireless power transmitter 2610 may be mounted
in each of the pads 2430 and 2440 of FIG. 24B. Additionally, the
wireless power transmitter 2610 may be mounted in the mobile
terminal 2540 of FIG. 25B.
[0271] In addition, a wireless power receiver 2620 may be mounted
in each of the hearing aids 2450 and 2460 of FIG. 24B.
[0272] The wireless power transmitter 2610 may have a similar
configuration to the source device 110 of FIG. 1. For example, the
wireless power transmitter 2610 may include a unit configured to
transmit power using magnetic coupling.
[0273] As illustrated in FIG. 26, the wireless power transmitter
2610 includes a communication/tracking unit 2611. The
communication/tracking unit 2611 may communicate with the wireless
power receiver 2620, and may control an impedance and a resonant
frequency to maintain a wireless power transmission efficiency.
Additionally, the communication/tracking unit 2611 may perform
similar functions to the power converter 114 and the
control/communication unit 115 of FIG. 1.
[0274] The wireless power receiver 2620 may have a similar
configuration to the target device 120 of FIG. 1. For example, the
wireless power receiver 2620 may include a unit configured to
wirelessly receive power and to charge a battery. As illustrated in
FIG. 26, the wireless power receiver 2620 includes a target
resonator, a rectifier, a DC/DC converter, and a charging circuit.
Additionally, the wireless power receiver 2620 may include a
control/communication unit 2623.
[0275] The communication/control unit 2623 may communicate with the
wireless power transmitter 2610, and may perform an operation to
protect overvoltage and overcurrent.
[0276] The wireless power receiver 2620 may include a hearing
device circuit 2621. The hearing device circuit 2621 may be charged
by the battery. The hearing device circuit 2621 may include a
microphone, an analog-to-digital converter (ADC), a processor, a
digital-to-analog converter (DAC), and a receiver. For example, the
hearing device circuit 2621 may have the same configuration as a
hearing aid.
[0277] The units described herein may be implemented using hardware
components and software components. For example, the hardware
components may include microphones, amplifiers, band-pass filters,
audio to digital convertors, and processing devices. A processing
device may be implemented using one or more general-purpose or
special purpose computers, such as, for example, a processor, a
controller and an arithmetic logic unit, a digital signal
processor, a microcomputer, a field programmable array, a
programmable logic unit, a microprocessor or any other device
capable of responding to and executing instructions in a defined
manner. The processing device may run an operating system (OS) and
one or more software applications that run on the OS. The
processing device also may access, store, manipulate, process, and
create data in response to execution of the software. For purpose
of simplicity, the description of a processing device is used as
singular; however, one skilled in the art will appreciated that a
processing device may include multiple processing elements and
multiple types of processing elements. For example, a processing
device may include multiple processors or a processor and a
controller. In addition, different processing configurations are
possible, such a parallel processors.
[0278] The software may include a computer program, a piece of
code, an instruction, or some combination thereof, for
independently or collectively instructing or configuring the
processing device to operate as desired. Software and data may be
embodied permanently or temporarily in any type of machine,
component, physical or virtual equipment, computer storage medium
or device, or in a propagated signal wave capable of providing
instructions or data to or being interpreted by the processing
device. The software also may be distributed over network coupled
computer systems so that the software is stored and executed in a
distributed fashion. In particular, the software and data may be
stored by one or more computer readable recording mediums. The
computer readable recording medium may include any data storage
device that can store data which can be thereafter read by a
computer system or processing device. Examples of the
non-transitory computer readable recording medium include read-only
memory (ROM), random-access memory (RAM), CD-ROMs, magnetic tapes,
floppy disks, optical data storage devices. Also, functional
programs, codes, and code segments for accomplishing the example
embodiments disclosed herein can be easily construed by programmers
skilled in the art to which the embodiments pertain based on and
using the flow diagrams and block diagrams of the figures and their
corresponding descriptions as provided herein.
[0279] A number of examples have been described above.
Nevertheless, it should be understood that various modifications
may be made. For example, suitable results may be achieved if the
described techniques are performed in a different order and/or if
components in a described system, architecture, device, or circuit
are combined in a different manner and/or replaced or supplemented
by other components or their equivalents. Accordingly, other
implementations are within the scope of the following claims.
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